Author Topic: Groestlcoin Core v2.16.0 Released  (Read 365 times)

Offline gruve_p

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Groestlcoin Core v2.16.0 Released
« on: June 22, 2018, 11:02:25 pm »

A new major Groestlcoin Core version 2.16.0 is now available for download bringing both new features and bug fixes, so it is recommended to upgrade to it if you are running a full Groestlcoin node or a local Groestlcoin Core wallet.


v2.16.0 is now the official release version of Groestlcoin Core. On top of the new features, various bugfixes, updated translations and performance improvements. It is recommended to upgrade to this version as soon as possible.


All pools, services, exchanges are already upgraded.
We would like to thank everybody for a smooth and fast upgrade (in no particular order):
supernova
sistemkoin
crypto wolf
coinexchange
xchange.me
neraex
stocks.exchange
bittylicious
chainrift
barterdex
binance
upbit
bittrex
coinrail
easyrabbit
coinpayments
cryptopia
livecoin
flyp.me
cointopay
trade satoshi
buybitcoin.org.in
coinswitch (doesnt use wallet)
coinmine.pl
coinomi
miningpoolhub
coinwarz (windows)
litebit (windows)
fubt.top (windows)
blazepool
reddit/irc bot
ooobtc
dwarfpool
coindelta
godex
instaswap
chainrift
koinok


What's new in version v2.16.0?
This is a major release of Groestlcoin Core with many protocol level improvements and code optimizations, featuring the technical equivalent of Bitcoin v0.16.0 but with Groestlcoin specific patches. On a general level, most of what is new is the ability to send/receive to/from bech32 addresses.

Changelog:
• Default transaction version bumped from 1 to 2.
• Qt version upgraded.
• Updated splash screen for mainnet and testnet.
• Icons Groestlized.
• Translations updated.
• Minimal fee lowered.
• Static builds for all platforms will be compiled from this release on.
• Validation speed and network propagation performance have been greatly improved, leading to much shorter sync and initial block download times.
• The script signature cache has been reimplemented as a "cuckoo cache", allowing for more signatures to be cached and faster lookups.
• Assumed-valid blocks have been introduced which allows script validation to be skipped for ancestors of known-good blocks, without changing the security model.
• In some cases, compact blocks are now relayed before being fully validated as per BIP152.
• P2P networking has been refactored with a focus on concurrency and throughput. Network operations are no longer bottlenecked by validation. As a result, block fetching is several times faster than previous releases in many cases.
• The UTXO cache now claims unused mempool memory. This speeds up initial block download as UTXO lookups are a major bottleneck there, and there is no use for the mempool at that stage.
• Groestlcoin Core has supported automatically pruning the blockchain since 2.11.0 Pruning the blockchain allows for significant storage space savings as the vast majority of the downloaded data can be discarded after processing so very little of it remains on the disk. Manual block pruning can now be enabled by setting `-prune=1`. Once that is set, the RPC command `pruneblockchain` can be used to prune the blockchain up to the specified height or timestamp.
• The `getinfo` RPC command has been deprecated. Each field in the RPC call has been moved to another command's output with that command also givingadditional information that `getinfo` did not provide. The following tableshows where each field has been moved to:
   |`getinfo` field   | Moved to                                  |
   |------------------|-------------------------------------------|
   `"version"`      | `getnetworkinfo()["version"]`
   `"protocolversion"`| `getnetworkinfo()["protocolversion"]`
   `"walletversion"`  | `getwalletinfo()["walletversion"]`
   `"balance"`      | `getwalletinfo()["balance"]`
   `"blocks"`      | `getblockchaininfo()["blocks"]`
   `"timeoffset"`      | `getnetworkinfo()["timeoffset"]`
   `"connections"`      | `getnetworkinfo()["connections"]`
   `"proxy"`      | `getnetworkinfo()["networks"][0]["proxy"]`
   `"difficulty"`      | `getblockchaininfo()["difficulty"]`
   `"testnet"`      | `getblockchaininfo()["chain"] == "test"`
   `"keypoololdest"`  | `getwalletinfo()["keypoololdest"]`
   `"keypoolsize"`      | `getwalletinfo()["keypoolsize"]`
   `"unlocked_until"` | `getwalletinfo()["unlocked_until"]`
   `"paytxfee"`      | `getwalletinfo()["paytxfee"]`
   `"relayfee"`      | `getnetworkinfo()["relayfee"]`
   `"errors"`      | `getnetworkinfo()["warnings"]`
• Previously the ZeroMQ notification system was unavailable on Windows due to various issues with ZMQ. These have been fixed upstream and
now ZMQ can be used on Windows.
• The ability to nest RPC commands has been added to the debug console. This allows users to have the output of a command become the input to another command without running the commands separately. The nested RPC commands use bracket syntax (i.e. `getwalletinfo()`) and can be nested (i.e. `getblock(getblockhash(1))`). Simple queries can be done with square brackets where object values are accessed with either an array index or a non-quoted string (i.e. `listunspent()[0][txid]`). Both
commas and spaces can be used to separate parameters in both the bracket syntax and normal RPC command syntax.
• A RPC command and GUI toggle have been added to enable or disable all p2p network activity. The network status icon in the bottom right hand corner is now the GUI toggle. Clicking the icon will either enable or disable all p2p network activity. If network activity is disabled, the icon will  be grayed out with an X on top of it.
• Additionally the `setnetworkactive` RPC command has been added which does the same thing as the GUI icon. The command takes one boolean parameter, `true` enables networking and `false` disables it.
• When Groestlcoin Core is out-of-sync on startup, a semi-transparent information layer will be shown over top of the normal display. This layer contains details about the current sync progress and estimates the amount of time remaining to finish syncing. This layer can also be hidden and subsequently unhidden by clicking on the progress bar at the bottom of the window.
• Commands sent over the JSON-RPC interface and through the `groestlcoin-cli` binary can now use named arguments. This follows the [JSON-RPC specification](http://www.jsonrpc.org/specification) for passing parameters by-name with an object. `groestlcoin-cli` has been updated to support this by parsing `name=value` arguments when the `-named` option is given. Some examples:
  - src/groestlcoin-cli -named help command="help"
  - src/groestlcoin-cli -named getblockhash height=0
  - src/groestlcoin-cli -named getblock blockhash=0000000000000036ae5aabb18a2d345d19d60ba1927f071af2aa8eec7a27d41d
  - src/groestlcoin-cli -named sendtoaddress address="(snip)" amount="1.0" subtractfeefromamount=true
The order of arguments doesn't matter in this case. Named arguments are also useful to leave out arguments that should stay at their default value. The rarely-used arguments `comment` and `comment_to` to `sendtoaddress`, for example, can be left out. However, this is not yet implemented for many RPC calls, this is expected to land in a later release. The RPC server remains fully backwards compatible with positional arguments.
• The debug console maintains a history of previously entered commands that can be accessed by pressing the Up-arrow key so that users can easily reuse previously entered commands. Commands which have sensitive information such as passphrases and private keys will now have a `(...)` in place of the parameters when accessed through the history.
• After resetting the options by clicking the `Reset Options` button in the options dialog or with the `-resetguioptions` startup option, the user will be prompted to choose the data directory again. This is to ensure that custom data directories will be kept after the option reset which clears the custom data directory set via the choose datadir dialog.
• Multiple peers can now be selected in the list of peers in the debug window. This allows for users to ban or disconnect multiple peers simultaneously instead of banning them one at a time.
• An indicator has been added to the bottom right hand corner of the main window to indicate whether the wallet being used is a HD wallet. This icon will be grayed out with an X on top of it if the wallet is not a HD wallet.
• UTXO set query (`GET /rest/getutxos/<checkmempool>/<txid>-<n>/<txid>-<n>/.../<txid>-<n>.<bin|hex|json>`) responses were changed to return status code `HTTP_BAD_REQUEST` (400) instead of `HTTP_INTERNAL_SERVER_ERROR` (500) when requests contain invalid parameters.
• Since the changes in 2.13.3 to automatically limit the size of the mempool and improve the performance of block creation in mining code it has not been important for relay nodes or miners to set `-minrelaytxfee`. With this release the following concepts that were tied to this option have been separated out:
   - incremental relay fee used for calculating BIP 125 replacement and mempool limiting. (1000 gros/kB)
   - calculation of threshold for a dust output. (effectively 3 * 1000 gros/kB)
   - minimum fee rate of a package of transactions to be included in a block created by the mining code. If miners wish to set this minimum they can use the new `-     blockmintxfee` option.  (defaults to 1000 gros/kB)
The `-minrelaytxfee` option continues to exist but is recommended to be left unset.
• Since 2.13.3 fee estimation for a confirmation target of 1 block has been disabled. The fee slider will no longer be able to choose a target of 1 block. This is only a minor behavior change as there was often insufficient data for this target anyway. `estimatefee 1` will now always return -1 and `estimatesmartfee 1` will start searching at a target of 2.
• The default target for fee estimation is changed to 6 blocks in both the GUI (previously 25) and for RPC calls (previously 2).
• Peers manually added through the `-addnode` option or `addnode` RPC now have their own limit of eight connections which does not compete with other inbound or outbound connection usage and is not subject to the limitation imposed by the `-maxconnections` option.
• New connections to manually added peers are performed more quickly.
• A significant portion of the initial block download time is spent verifying scripts/signatures.  Although the verification must pass to ensure the security of the system, no other result from this verification is needed: If the node knew the history of a given block were valid it could skip checking scripts for its ancestors.
• A new configuration option 'assumevalid' is provided to express this knowledge to the software.  Unlike the 'checkpoints' in the past this setting does not force the use of a particular chain: chains that are consistent with it are processed quicker, but other chains are still accepted if they'd otherwise be chosen as best. Also unlike 'checkpoints' the user can configure which block history is assumed true, this means that even outdated software can sync more quickly if the setting is updated by the user.
• Because the validity of a chain history is a simple objective fact it is much easier to review this setting.  As a result the software ships with a default value adjusted to match the current chain shortly before release.  The use of this default value can be disabled by setting -assumevalid=0
• Before 2.16, `fundrawtransaction` was by default wallet stateless. In almost all cases `fundrawtransaction` does add a change-output to the outputs of the funded transaction. Before 2.16, the used keypool key was never marked as change-address key and directly returned to the keypool (leading to address reuse).  Before 2.16, calling `getnewaddress` directly after `fundrawtransaction` did generate the same address as the change-output address.
• Since 2.16, fundrawtransaction does reserve the change-output-key from the keypool by default (optional by setting  `reserveChangeKey`, default =`true`)
• Users should also consider using `getrawchangeaddress()` in conjunction with `fundrawtransaction`'s `changeAddress` option.
• Before 2.16, memory reserved for mempool (using the `-maxmempool` option) went unused during initial block download, or IBD. In 2.16, the UTXO DB cache (controlled with the `-dbcache` option) borrows memory from the mempool when there is extra memory available. This may result in an increase in memory usage during IBD for those previously relying on only the `-dbcache` option to limit memory during that time.
• In previous versions, getblocktemplate required segwit support from downstream clients/miners once the feature activated on the network. In this version, it now supports non-segwit clients even after activation, by removing all segwit transactions from the returned block template. This allows non-segwit miners to continue functioning correctly even after segwit has activated.
• Due to the limitations in previous versions, getblocktemplate also recommended non-segwit clients to not signal for the segwit version-bit. Since this is no longer an issue, getblocktemplate now always recommends signalling segwit for all miners. This is safe because ability to enforce the rule is the only required criteria for safe activation, not actually producing segwit-enabled blocks.
• Memory usage for the UTXO cache is being calculated more accurately, so that the configured limit (`-dbcache`) will be respected when memory usage peaks
during cache flushes.  The memory accounting in prior releases is estimated to only account for half the actual peak utilization.
• The default `-dbcache` has also been changed in this release to 450MiB.  Users who currently set `-dbcache` to a high value (e.g. to keep the UTXO more fully
cached in memory) should consider increasing this setting in order to achieve the same cache performance as prior releases.  Users on low-memory systems (such as systems with 1GB or less) should consider specifying a lower value for this parameter.
• Bundled miniupnpc was updated to 2.0.20170509. This fixes an integer signedness error (present in MiniUPnPc v1.4.20101221 through v2.0) that allows remote attackers
(within the LAN) to cause a denial of service or possibly have unspecified other impact. This only affects users that have explicitly enabled UPnP through the GUI
setting or through the `-upnp` option, as since the last UPnP vulnerability (in Groestlcoin Core 2.1.0.6) it has been disabled by default. If you use this option, it is recommended to upgrade to this version as soon as possible.
• The chainstate database (which is used for tracking UTXOs) has been changed from a per-transaction model to a per-output model . Advantages of this model are that it:
    - avoids the CPU overhead of deserializing and serializing the unused outputs;
    - has more predictable memory usage;
    - uses simpler code;
    - is adaptable to various future cache flushing strategies.
As a result, validating the blockchain during Initial Block Download (IBD) and reindex is ~30-40% faster, uses 10-20% less memory, and flushes to disk far less frequently. The only downside is that the on-disk database is 15% larger. During the conversion from the previous format a few extra gigabytes may be used.
• Earlier versions experienced a spike in memory usage while flushing UTXO updates to disk. As a result, only half of the available memory was actually used as cache, and the other half was reserved to accommodate flushing. This is no longer the case, and the entirety of the available cache (see `-dbcache`) is now actually used as cache. This reduces the flushing frequency by a factor 2 or more.
• In previous versions, signature validation for transactions has been cached when the transaction is accepted to the mempool. Version 2.16 extends this to cache the entire script validity. This means that if a transaction in a block has already been accepted to the mempool, the scriptSig does not need to be re-evaluated. Empirical tests show that this results in new block validation being 40-50% faster.
• LevelDB has been upgraded to version 1.20. This version contains hardware acceleration for CRC on architectures supporting SSE 4.2. As a result, synchronization and block validation are now faster.
• Refill of the keypool no longer flushes the wallet between each key which resulted in a ~20x speedup in creating a new wallet. Part of this speedup was used to increase the default keypool to 1000 keys to make recovery more robust.
• Fee estimation has been significantly improved in version 2.16, with more accurate fee estimates used by the wallet and a wider range of options for advanced users of the `estimatesmartfee` and `estimaterawfee` RPCs.
• Internally, estimates are now tracked on 3 different time horizons. This allows for longer targets and means estimates adjust more quickly to changes in conditions.
• Estimates can now be conservative or economical. Conservative estimates use longer time horizons to produce an estimate which is less susceptible to rapid changes in fee conditions. Economical estimates use shorter time horizons and will be more affected by short-term changes in fee conditions. Economical estimates may be considerably lower during periods of low transaction activity (for example over weekends), but may result in transactions being unconfirmed if prevailing fees increase rapidly.
• By default, the wallet will use conservative fee estimates to increase the reliability of transactions being confirmed within the desired target. For transactions that are marked as replaceable, the wallet will use an economical estimate by default, since the fee can be 'bumped' if the fee conditions change rapidly.
• Estimates can now be made for confirmation targets up to 1008 blocks (one day).
• More data on historical fee rates is stored, leading to more precise fee estimates.
• Transactions which leave the mempool due to eviction or other non-confirmed reasons are now taken into account by the fee estimation logic, leading to more accurate fee estimates.
• The fee estimation logic will make sure enough data has been gathered to return a meaningful estimate. If there is insufficient data, a fallback default fee is used.
• The `estimatefee` RPC is now deprecated in favor of using only `estimatesmartfee` (which is the implementation used by the GUI)
• The `estimatesmartfee` RPC interface has been changed:
    - The `nblocks` argument has been renamed to `conf_target` (to be consistent with other RPC methods).
    - An `estimate_mode` argument has been added. This argument takes one of the following strings: `CONSERVATIVE`, `ECONOMICAL` or `UNSET` (which defaults to             `CONSERVATIVE`).
    - The RPC return object now contains an `errors` member, which returns errors encountered during processing.
    - If Groestlcoin Core has not been running for long enough and has not seen enough blocks or transactions to produce an accurate fee estimation, an error will be returned (previously a value of -1 was used to indicate an error, which could be confused for a feerate).
• A new `estimaterawfee` RPC is added to provide raw fee data. External clients can query and use this data in their own fee estimation logic.
• Groestkcoin Core now supports loading multiple, separate wallets. The wallets are completely separated, with individual balances, keys and received transactions. Multi-wallet is enabled by using more than one `-wallet` argument when starting Groestlcoin, either on the command line or in the Groestlcoin config file. In Groestlcoin-Qt, only the first wallet will be displayed and accessible for creating and signing transactions. GUI selectable multiple wallets will be supported in a future version. However, even in 2.16 other loaded wallets will remain synchronized to the node's current tip in the background. This can be useful if running a pruned node, since loading a wallet where the most recent sync is beyond the pruned height results in having to download and revalidate the whole blockchain. Continuing to synchronize all wallets in the background avoids this problem. Note that while multi-wallet is now fully supported, the RPC multi-wallet interface should be considered unstable for version 2.16.0, and there may backwards-incompatible changes in future versions.
• When running Groestlcoin Core with a single wallet, there are no changes to the RPC interface or `groestlcoin-cli`. All RPC calls and `groestlcoin-cli` commands continue to work as before.
• When running Groestlcoin Core with multi-wallet, all node-level RPC methods continue to work as before. HTTP RPC requests should be send to the normal `<RPC IP address>:<RPC port>` endpoint, and `groestlcoin-cli` commands should be run as before. A node-level RPC method is any method which does not require access to the wallet.
• When running Groestlcoin Core with multi-wallet, wallet-level RPC methods must specify the wallet for which they're intended in every request. HTTP RPC requests should be send to the `<RPC IP address>:<RPC port>/wallet/<wallet name>` endpoint, for example `127.0.0.1:1441/wallet/wallet1.dat`. `groestlcoin-cli` commands should be run with a `-rpcwallet` option, for example `groestlcoin-cli -rpcwallet=wallet1.dat getbalance`.
• A new node-level `listwallets` RPC method is added to display which wallets are currently loaded. The names returned by this method are the same as those used in the HTTP endpoint and for the `rpcwallet` argument.
• Groestlcoin Core has supported creating opt-in replace-by-fee (RBF) transactions since version 2.13.3. In version 2.16, creating an opt-in RBF transaction and replacing the unconfirmed transaction with a higher-fee transaction are both supported in the GUI.
• The concept of *free transactions* has been removed. High Coin Age Priority transactions would previously be allowed to be relayed even if they didn't attach a miner fee. This is no longer possible since there is no concept of Coin Age Priority. The `-limitfreerelay` and `-relaypriority` options which controlled relay of free transactions have therefore been removed.
• The `-sendfreetransactions` option has been removed, since almost all miners do not include transactions which do not attach a transaction fee.
• The `-blockprioritysize` option has been removed.
• The `estimatepriority` and `estimatesmartpriority` RPCs have been removed.
• The `getmempoolancestors`, `getmempooldescendants`, `getmempoolentry` and `getrawmempool` RPCs no longer return `startingpriority` and `currentpriority`.
• The `prioritisetransaction` RPC no longer takes a `priority_delta` argument, which is replaced by a `dummy` argument for backwards compatibility with clients using positional arguments. The RPC is still used to change the apparent fee-rate of the transaction by using the `fee_delta` argument.
• `-minrelaytxfee` can now be set to 0. If `minrelaytxfee` is set, then fees smaller than `minrelaytxfee` (per kB) are rejected from relaying, mining and transaction creation. This defaults to 10000 gro/kB.
• The `-printpriority` option has been updated to only output the fee rate and hash of transactions included in a block by the mining code.
• Version 2.16 introduced mempool persistence across restarts (the mempool is saved to a `mempool.dat` file in the data directory prior to shutdown and restores the mempool when the node is restarted). Version 2.16 also allows this feature to be switched on or off using the `-persistmempool` command-line optio. By default, the option is set to true, and the mempool is saved on shutdown and reloaded on startup. If set to false, the `mempool.dat` file will not be loaded on startup or saved on shutdown.
• A number of changes to the way Groestlcoin Core deals with peer connections and invalid blocks have been made, as a safety precaution against blockchain forks and misbehaving peers.
• Unrequested blocks with less work than the minimum-chain-work are now no longer processed even if they have more work than the tip (a potential issue during IBD where the tip may have low-work). This prevents peers wasting the resources of a node.
• Peers which provide a chain with less work than the minimum-chain-work during IBD will now be disconnected.
• For a given outbound peer, we now check whether their best known block has at least as much work as our tip. If it doesn't, and if we still haven't heard about a block with sufficient work after a 20 minute timeout, then we send a single getheaders message, and wait 2 more minutes. If after two minutes their best known block has insufficient work, we disconnect that peer. We protect 4 of our outbound peers from being disconnected by this logic to prevent excessive network topology changes as a result of this algorithm, while still ensuring that we have a reasonable number of nodes not known to be on bogus chains.
• Outbound (non-manual) peers that serve us block headers that are already known to be invalid (other than compact block announcements, because BIP 152 explicitly permits nodes to relay compact blocks before fully validating them) will now be disconnected.
• If the chain tip has not been advanced for over 30 minutes, we now assume the tip may be stale and will try to connect to an additional outbound peer. A periodic check ensures that if this extra peer connection is in use, we will disconnect the peer that least recently announced a new block.
• The set of all known invalid-themselves blocks (i.e. blocks which we attempted to connect but which were found to be invalid) are now tracked and used to check if new headers build on an invalid chain. This ensures that everything that descends from an invalid block is marked as such.
• Though blockmaxweight has been preferred for limiting the size of blocks returned by getblocktemplate since 2.13.3, blockmaxsize remained as an option for those who wished to limit their block size directly. Using this option resulted in a few UI issues as well as non-optimal fee selection and ever-so-slightly worse performance, and has thus now been deprecated. Further, the blockmaxsize option is now used only to calculate an implied blockmaxweight, instead of limiting block size directly. Any miners who wish to limit their blocks by size, instead of by weight, will have to do so manually by removing transactions from their block template directly.
• The GUI settings will now be written to `guisettings.ini.bak` in the data directory before wiping them when the `-resetguisettings` argument is used. This can be used to retroactively troubleshoot issues due to the GUI settings.
• A hidden debug argument `-minimumchainwork` has been added to allow a custom minimum work value to be used when validating a chain.
• Groestlcoin Core 2.16.0 introduces full support for segwit in the wallet and user interfaces. A new `-addresstype` argument has been added, which supports `legacy`, `p2sh-segwit` (default), and `bech32` addresses. It controls what kind of addresses are produced by `getnewaddress`, `getaccountaddress`, and `createmultisigaddress`. A `-changetype` argument has also been added, with the same options, and by default equal to `-addresstype`, to control which kind of change is used.
• A new `address_type` parameter has been added to the `getnewaddress` and `addmultisigaddress` RPCs to specify which type of address to generate.
• A `change_type` argument has been added to the `fundrawtransaction` RPC to override the `-changetype` argument for specific transactions.
• All segwit addresses created through `getnewaddress` or `*multisig` RPCs explicitly get their redeemscripts added to the wallet file. This means that downgrading after creating a segwit address will work, as long as the wallet file is up to date.
• All segwit keys in the wallet get an implicit redeemscript added, without it being written to the file. This means recovery of an old backup will work, as long as you use new software.
• All keypool keys that are seen used in transactions explicitly get their redeemscripts added to the wallet files. This means that downgrading after recovering from a backup that includes a segwit address will work
• Note that some RPCs do not yet support segwit addresses. Notably, `signmessage`/`verifymessage` doesn't support segwit addresses, nor does `importmulti` at this time. Support for segwit in those RPCs will continue to be added in future versions.
• P2WPKH change outputs are now used by default if any destination in the transaction is a P2WPKH or P2WSH output. This is done to ensure the change output is as indistinguishable from the other outputs as possible in either case.
• Full support for native segwit addresses (BIP173 / Bech32) has now been added. This includes the ability to send to BIP173 addresses (including non-v0 ones), and generating these addresses.
• A checkbox has been added to the GUI to select whether a Bech32 address or P2SH-wrapped address should be generated when using segwit addresses. When launched with `-addresstype=bech32` it is checked by default. When launched with `-addresstype=legacy` it is unchecked and disabled.
• Due to a backward-incompatible change in the wallet database, wallets created with version 2.16.0 will be rejected by previous versions. Also, version 2.16.0
will only create hierarchical deterministic (HD) wallets. Note that this only applies to new wallets; wallets made with previous versions will not be upgraded to be HD.
• The send screen now uses RBF by default, regardless of `-walletrbf`. There is a checkbox to mark the transaction as final.
• The RPC default remains unchanged: to use RBF, launch with `-walletrbf=1` or use the `replaceable` argument for individual transactions.
• Groestlcoin Core now has more flexibility in where the wallets directory can be located. Previously wallet database files were stored at the top level of the groestlcoin data directory. The behavior is now:
  - For new installations (where the data directory doesn't already exist), wallets will now be stored in a new `wallets/` subdirectory inside the data directory by     default.
  - For existing nodes (where the data directory already exists), wallets will be stored in the data directory root by default. If a `wallets/` subdirectory already        exists in the data directory root, then wallets will be stored in the `wallets/` subdirectory by default.
  - The location of the wallets directory can be overridden by specifying a `-walletdir=<path>` option where `<path>` can be an absolute path to a directory or     directory symlink.
  Care should be taken when choosing the wallets directory location, as if it becomes unavailable during operation, funds may be lost.
• The minimum version of the GCC compiler required to compile Groestlcoin Core is now 4.8. No effort will be made to support older versions of GCC. The minimum version for the Clang compiler is still 3.3. Other minimum dependency versions can be found in `doc/dependencies.md` in the repository.
• Pruned nodes can now signal BIP159's NODE_NETWORK_LIMITED using service bits, in preparation for full BIP159 support in later versions. This would allow pruned nodes to serve the most recent blocks. However, the current change does not yet include support for connecting to these pruned peers.
• The SHA256 hashing optimizations for architectures supporting SSE4, which lead to ~50% speedups in SHA256 on supported hardware (~5% faster synchronization and block validation), have now been enabled by default. In previous versions they were enabled using the `--enable-experimental-asm` flag when building, but are now the default and no longer deemed experimental.
• Uses of "µGRS" in the GUI now also show the more colloquial term "groestls".
• The option to reuse a previous address has now been removed. This was justified by the need to "resend" an invoice, but now that we have the request history, that need should be gone.
• Support for searching by TXID has been added, rather than just address and label.
• A "Use available balance" option has been added to the send coins dialog, to add the remaining available wallet balance to a transaction output.
• A toggle for unblinding the password fields on the password dialog has been added.
• Safe mode is now disabled by default and must be manually enabled (with `-disablesafemode=0`) if you wish to use it. Safe mode is a feature that disables a subset of RPC calls - mostly related to the wallet and sending - automatically in case certain problem conditions with the network are detected. However, developers have come to regard these checks as not reliable enough to act on automatically. Even with safe mode disabled, they will still cause warnings in the `warnings` field of the `getneworkinfo` RPC and launch the `-alertnotify` command.
• The `share/rpcuser/rpcuser.py` script was renamed to `share/rpcauth/rpcauth.py`. This script can be used to create `rpcauth` credentials for a JSON-RPC user.
• A new field `iswitness` is True for P2WPKH and P2WSH addresses ("grs1..." addresses), but not for P2SH-wrapped segwit addresses.
• The existing field `isscript` will now also report True for P2WSH addresses.
• A new field `embedded` is present for all script addresses where the script is known and matches something that can be interpreted as a known address. This is particularly true for P2SH-P2WPKH and P2SH-P2WSH addresses. The value for `embedded` includes much of the information `validateaddress` would report if invoked directly on the embedded address.
• For multisig scripts a new `pubkeys` field was added that reports the full public keys involved in the script (if known). This is a replacement for the existing `addresses` field (which reports the same information but encoded as P2PKH addresses), represented in a more useful and less confusing way. The `addresses` field remains present for non-segwit addresses for backward compatibility.
• For all single-key addresses with known key (even when wrapped in P2SH or P2WSH), the `pubkey` field will be present. In particular, this means that invoking `validateaddress` on the output of `getnewaddress` will always report the `pubkey`, even when the address type is P2SH-P2WPKH.
• `importprunedfunds` only accepts two required arguments. Some versions accept an optional third arg, which was always ignored. Make sure to never pass more than two arguments.
• The first boolean argument to `getaddednodeinfo` has been removed. This is an incompatible change.
• RPC command `getmininginfo` loses the "testnet" field in favor of the more generic "chain" (which has been present for years).
• A new RPC command `preciousblock` has been added which marks a block as precious. A precious block will be treated as if it were received earlier than a competing block.
• A new RPC command `importmulti` has been added which receives an array of  JSON objects representing the intention of importing a public key, a private key, an address and script/p2sh.
• Use of `getrawtransaction` for retrieving confirmed transactions with unspent outputs has been deprecated. For now this will still work, but in the future it may change to only be able to retrieve information about transactions in the mempool or if `txindex` is enabled.
• A new RPC command `getmemoryinfo` has been added which will return information about the memory usage of groestlcoin Core. This was added in conjunction with optimizations to memory management.
• A new RPC command `bumpfee` has been added which allows replacing an unconfirmed wallet transaction that signaled RBF with a new transaction that pays a higher fee, and should be more likely to get confirmed quickly.
• The "currentblocksize" value in getmininginfo has been removed.
• `dumpwallet` no longer allows overwriting files. This is a security measure as well as prevents dangerous user mistakes.
• `backupwallet` will now fail when attempting to backup to source file, rather than destroying the wallet.
• `listsinceblock` will now throw an error if an unknown `blockhash` argument value is passed, instead of returning a list of all wallet transactions since the genesis block. The behaviour is unchanged when an empty string is provided.
• A new RPC `rescanblockchain` has been added to manually invoke a blockchain rescan. The RPC supports start and end-height arguments for the rescan, and can be used in a multiwallet environment to rescan the blockchain at runtime.
• A new `savemempool` RPC has been added which allows the current mempool to be saved to disk at any time to avoid it being lost due to crashes / power loss.
• The first positional argument of `createrawtransaction` was renamed from `transactions` to `inputs`.
• The argument of `disconnectnode` was renamed from `node` to `address`.
• `abortrescan` stops current wallet rescan, e.g. when triggered by an `importprivkey` call.
• `combinerawtransaction` accepts a JSON array of raw transactions and combines them into a single raw transaction.
• `estimaterawfee` returns raw fee data so that customized logic can be implemented to analyze the data and calculate estimates. See for full details on changes to the fee estimation logic and interface.
• `getchaintxstats` returns statistics about the total number and rate of transactions in the chain.
• `listwallets` lists wallets which are currently loaded.
• `uptime` returns the total runtime of the `groestlcoind` server since its last start.
• When using Groestlcoin Core in multi-wallet mode, RPC requests for wallet methods must specify the wallet that they're intended for.
• The new database model no longer stores information about transaction versions of unspent outputs. This means that:
  - The `gettxout` RPC no longer has a `version` field in the response.
  - The `gettxoutsetinfo` RPC reports `hash_serialized_2` instead of `hash_serialized`, which does not commit to the transaction versions of unspent outputs, but does
    commit to the height and coinbase information.
  - The `getutxos` REST path no longer reports the `txvers` field in JSON format, and always reports 0 for transaction versions in the binary format
• The `estimatefee` RPC is deprecated. Clients should switch to using the `estimatesmartfee` RPC, which returns better fee estimates. See for full details on changes to the fee estimation logic and interface.
• The `gettxoutsetinfo` response now contains `disk_size` and `bogosize` instead of `bytes_serialized`. The first is a more accurate estimate of actual disk usage, but is not deterministic. The second is unrelated to disk usage, but is a database-independent metric of UTXO set size: it counts every UTXO entry as 50 + the length of its scriptPubKey.
• `signrawtransaction` can no longer be used to combine multiple transactions into a single transaction. Instead, use the new `combinerawtransaction` RPC.
• `fundrawtransaction` no longer accepts a `reserveChangeKey` option. This option used to allow RPC users to fund a raw transaction using an key from the keypool for the change address without removing it from the available keys in the keypool. The key could then be re-used for a `getnewaddress` call, which could potentially result in confusing or dangerous behaviour.
• `estimatepriority` and `estimatesmartpriority` have been removed.
• The `listunspent` RPC now takes a `query_options` argument, which is a JSON object containing one or more of the following members:
  - `minimumAmount` - a number specifying the minimum value of each UTXO
  - `maximumAmount` - a number specifying the maximum value of each UTXO
  - `maximumCount` - a number specifying the minimum number of UTXOs
  - `minimumSumAmount` - a number specifying the minimum sum value of all UTXOs
• The `getmempoolancestors`, `getmempooldescendants`, `getmempoolentry` and `getrawmempool` RPCs no longer return `startingpriority` and `currentpriority`.
• The `dumpwallet` RPC now returns the full absolute path to the dumped wallet. It used to return no value, even if successful.
• In the `getpeerinfo` RPC, the return object for each peer now returns an `addrbind` member, which contains the ip address and port of the connection to the peer. This is in addition to the `addrlocal` member which contains the ip address and port of the local node as reported by the peer.
• The `disconnectnode` RPC can now disconnect a node specified by node ID (as well as by IP address/port). To disconnect a node based on node ID, call the RPC with the new `nodeid` argument.
• The second argument in `prioritisetransaction` has been renamed from `priority_delta` to `dummy` since Groestlcoin Core no longer has a concept of coin age priority. The `dummy` argument has no functional effect, but is retained for positional argument compatibility.
• The `resendwallettransactions` RPC throws an error if the `-walletbroadcast` option is set to false.
• The second argument in the `submitblock` RPC argument has been renamed from `parameters` to `dummy`. This argument never had any effect, and the renaming is simply to communicate this fact to the user (Clients should, however, use positional arguments for `submitblock` in order to be compatible with BIP 22.)
• The `verbose` argument of `getblock` has been renamed to `verbosity` and now takes an integer from 0 to 2. Verbose level 0 is equivalent to `verbose=false`. Verbose level 1 is equivalent to `verbose=true`. Verbose level 2 will give the full transaction details of each transaction in the output as given by `getrawtransaction`. The old behavior of using the `verbose` named argument and a boolean value is still maintained for compatibility.
• `getblock` now returns RPC_MISC_ERROR if the block can't be found on disk (for example if the block has been pruned). Previously returned RPC_INTERNAL_ERROR.
• `pruneblockchain` now returns RPC_MISC_ERROR if the blocks cannot be pruned because the node is not in pruned mode. Previously returned RPC_METHOD_NOT_FOUND.
• `pruneblockchain` now returns RPC_INVALID_PARAMETER if the blocks cannot be pruned because the supplied timestamp is too late. Previously returned RPC_INTERNAL_ERROR.
• `pruneblockchain` now returns RPC_MISC_ERROR if the blocks cannot be pruned because the blockchain is too short. Previously returned RPC_INTERNAL_ERROR.
• `setban` now returns RPC_CLIENT_INVALID_IP_OR_SUBNET if the supplied IP address or subnet is invalid. Previously returned RPC_CLIENT_NODE_ALREADY_ADDED.
• `setban` now returns RPC_CLIENT_INVALID_IP_OR_SUBNET if the user tries to unban a node that has not previously been banned. Previously returned RPC_MISC_ERROR.
• `removeprunedfunds` now returns RPC_WALLET_ERROR if `groestlcoind` is unable to remove the transaction. Previously returned RPC_INTERNAL_ERROR.
• `removeprunedfunds` now returns RPC_INVALID_PARAMETER if the transaction does not exist in the wallet. Previously returned RPC_INTERNAL_ERROR.
• `fundrawtransaction` now returns RPC_INVALID_ADDRESS_OR_KEY if an invalid change address is provided. Previously returned RPC_INVALID_PARAMETER.
• `fundrawtransaction` now returns RPC_WALLET_ERROR if `groestlcoind` is unable to create the transaction. The error message provides further details. Previously returned RPC_INTERNAL_ERROR.
• `bumpfee` now returns RPC_INVALID_PARAMETER if the provided transaction has descendants in the wallet. Previously returned RPC_MISC_ERROR.
• `bumpfee` now returns RPC_INVALID_PARAMETER if the provided transaction has descendants in the mempool. Previously returned RPC_MISC_ERROR.
• `bumpfee` now returns RPC_WALLET_ERROR if the provided transaction has has been mined or conflicts with a mined transaction. Previously returned RPC_INVALID_ADDRESS_OR_KEY.
• `bumpfee` now returns RPC_WALLET_ERROR if the provided transaction is not BIP 125 replaceable. Previously returned RPC_INVALID_ADDRESS_OR_KEY.
• `bumpfee` now returns RPC_WALLET_ERROR if the provided transaction has already been bumped by a different transaction. Previously returned RPC_INVALID_REQUEST.
• `bumpfee` now returns RPC_WALLET_ERROR if the provided transaction contains inputs which don't belong to this wallet. Previously returned RPC_INVALID_ADDRESS_OR_KEY.
• `bumpfee` now returns RPC_WALLET_ERROR if the provided transaction has multiple change outputs. Previously returned RPC_MISC_ERROR.
• `bumpfee` now returns RPC_WALLET_ERROR if the provided transaction has no change output. Previously returned RPC_MISC_ERROR.
• `bumpfee` now returns RPC_WALLET_ERROR if the fee is too high. Previously returned RPC_MISC_ERROR.
• `bumpfee` now returns RPC_WALLET_ERROR if the fee is too low. Previously returned RPC_MISC_ERROR.
• `bumpfee` now returns RPC_WALLET_ERROR if the change output is too small to bump the fee. Previously returned RPC_MISC_ERROR.
• The deprecated RPC `getinfo` was removed. It is recommended that the more specific RPCs are used: `getblockchaininfo` `getnetworkinfo` `getwalletinfo` `getmininginfo`
• The wallet RPC `getreceivedbyaddress` will return an error if called with an address not in the wallet.
• The wallet RPC `addwitnessaddress` was deprecated and will be removed in future version, set the `address_type` argument of `getnewaddress`, or option `-addresstype=[bech32|p2sh-segwit]` instead.
• `dumpwallet` now includes hex-encoded scripts from the wallet in the dumpfile, and `importwallet` now imports these scripts, but corresponding addresses may not be added correctly or a manual rescan may be required to find relevant transactions.
• The RPC `getblockchaininfo` now includes an `errors` field.
• A new `blockhash` parameter has been added to the `getrawtransaction` RPC which allows for a raw transaction to be fetched from a specific block if known, even without `-txindex` enabled.
• The `decoderawtransaction` and `fundrawtransaction` RPCs now have optional `iswitness` parameters to override the heuristic witness checks if necessary.
• The `walletpassphrase` timeout is now clamped to 2^30 seconds.
• Using addresses with the `createmultisig` RPC is now deprecated, and will be removed in a later version. Public keys should be used instead.
• Blockchain rescans now no longer lock the wallet for the entire rescan process, so other RPCs can now be used at the same time (although results of balances / transactions may be incorrect or incomplete until the rescan is complete).
• The `logging` RPC has now been made public rather than hidden.
• An `initialblockdownload` boolean has been added to the `getblockchaininfo` RPC to indicate whether the node is currently in IBD or not.
• `minrelaytxfee` is now included in the output of `getmempoolinfo`
• `-debuglogfile=<file>` can be used to specify an alternative debug logging file.
• groestlcoin-cli now has an `-stdinrpcpass` option to allow the RPC password to be read from standard input.
• The `-usehd` option has been removed.
• groestlcoin-cli now supports a new `-getinfo` flag which returns an output like that of the now-removed `getinfo` RPC.
• Regtest support has been enabled and the JSON-RPC port is 18888.
• Segwit is always active in regtest mode by default.

It is appreciated if feedback of the following is provided:
1. Can you receive coins on a bech32 address? (small amounts to avoid losing them)
2. Can you receive coins on a legacy address? (small amounts to avoid losing them)
3. Can you receive coins on a p2sh-segwit address? (small amounts to avoid losing them)
4. Can you send coins on a bech32 address?
5. Can you send coins on a legacy address?
6. Can you send coins on a p2sh-segwit address?
7. Can you view your transaction on a third party blockexplorer (restart the client after entering the url of the blockexplorer) ?
8. Can you use the wallet with TOR?
9. Are you able to backup your wallet (wallet.dat) file?
10. Are you able to encrypt your wallet (wallet.dat) file?
11. Are you able to use watch-only function?
12. How long does it take to fully synchronize?
13. Are you able to sign/verify messages?
14. Are you able to see you send/receive addresses?
15. Are you able to use the wallet in your local language?

The application may have unfound bugs and problems. Please report using the issue tracker at github:
https://github.com/groestlcoin/groestlcoin/issues

Important:
• There is no warranty and no party shall be made liable to you for damages. If you lose coins due to this app, no compensation will be given. Use this app solely at your own risk.
• Encrypt your wallet. This can be done by clicking the settings menu from inside the wallet. Make sure your password is secure and do not forget it.
• Make a copy your wallet.dat file as a backup and move it to a secure location:
Location Windows: Navigate to C:\Users\Username\AppData\Roaming\groestlcoin\wallet.dat (or open windows explorer and enter %appdata%\Groestlcoin\wallet.dat)
Location Mac: Finder -> Go {Hold Option] -> Library -> groestlcoin -> wallet.dat (~/Library/Application Support/groestlcoin/wallet.dat)

WARNING:
While this branch has been extensively tested to be compatible with the existing Groestlcoin v2.11.0 and v2.13.3 network there is the possibility that we missed something. ALWAYS BACKUP YOUR GROESTLCOIN WALLET BEFORE UPGRADING.


How to Upgrade?
The first time you run version 2.16.0, your chainstate database will be converted to a new format, which will take anywhere from a few minutes to half an hour, depending on the speed of your machine.
Windows: If you are running an older version, shut it down. Wait until it has completely shut down (which might take a few minutes for older versions), then run the installer.
OSX: If you are running an older version, shut it down. Wait until it has completely shut down (which might take a few minutes for older versions), run the dmg and drag Groestlcoin Core to Applications.
Ubuntu users: http://groestlcoin.org/forum/index.php?topic=441.0
Linux users: http://groestlcoin.org/forum/index.php?topic=97.0

Download the Windows Installer (64 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-win64.msi
Download the Windows Installer (32 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-win32.msi
Download the Windows binaries (64 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-x86_64-w64-mingw32.zip
Download the Windows binaries (32 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-i686-w64-mingw32.zip
Download the OSX Installer here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-osx.dmg
Download the OSX binaries here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-x86_64-apple-darwin11.tar.gz
Download the Linux binaries (64 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-x86_64-linux-gnu.tar.gz
Download the Linux binaries (32 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-i686-pc-linux-gnu.tar.gz
Download the ARM Linux binaries (64 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-aarch64-linux-gnu.tar.gz
Download the ARM Linux binaries (32 bit) here: https://github.com/Groestlcoin/groestlcoin/releases/download/v2.16.0/groestlcoin-2.16.0-arm-linux-gnueabihf.tar.gz

SHA-256 hashes of the released files for verification:
groestlcoin-2.16.0-x86_64-linux-gnu.tar.gz 4e7683bbc6f3b7899761d1360f52a91f417e2b7e6c56b75b522d95b86ca46628
groestlcoin-2.16.0-aarch64-linux-gnu.tar.gz
a04c37bbc384387e1587ad7dd3c85cdfde71a351d9825cdc915898f943b8665c
groestlcoin-2.16.0-arm-linux-gnueabihf.tar.gz
1d0bec5e2073717d20aae63d957e9e404ce0ed26a8757a6cdd3ac68ee809ead6
groestlcoin-2.16.0-i686-pc-linux-gnu.tar.gz
ecd8b437995e1806138816a3dc20765058b8933bbdbfa5d87bcafe01b76f9324
groestlcoin-2.16.0-osx.dmg
fb2984cf2f27a2369bfcbe9674a3cc0f9a09835701372b7a51562b6f2d596729
groestlcoin-2.16.0-win64.msi
6ee50fd6d579ce19a7d49d07fa5f910b3316ab37ebb692571601c74d75493620
groestlcoin-2.16.0-win32.msi
f717a1bd8d6d1c4220c79f17b92eb9f2c7a292a6d0801fa83b58d8e3dc7e8c93
groestlcoin-2.16.0-x86_64-w64-mingw32.zip
327aaee189255f2722736a426732a0f38fef90bae6495f42fd148138523c586c
groestlcoin-2.16.0-i686-w64-mingw32.zip
4107659e268f1e4143bd7c8d7f7ffe1653fea95eca66de4259175585652306cd
groestlcoin-2.16.0-x86_64-apple-darwin11.tar.gz
5ff6e5a509e0c69f4a832bd3c40a1a93f80a68bc5f55a0b5d517716fb123164e

Source code:
https://github.com/Groestlcoin/groestlcoin
Build instructions for Linux can be found here: https://github.com/Groestlcoin/groestlcoin/blob/master/doc/build-unix.md
Build instructions for OSX can be found here: https://github.com/Groestlcoin/groestlcoin/blob/master/doc/build-osx.md
Build instructions for Windows can be found here: https://github.com/Groestlcoin/groestlcoin/blob/master/doc/build-windows.md