bitcoin/doc/release-notes.md

(note: this is a temporary file, to be added-to by anybody, and moved to release-notes at release time)

Bitcoin Core version version is now available from:

https://bitcoincore.org/bin/bitcoin-core-*version*/

This is a new major version release, including new features, various bugfixes and performance improvements, as well as updated translations.

Please report bugs using the issue tracker at GitHub:

https://github.com/bitcoin/bitcoin/issues

To receive security and update notifications, please subscribe to:

https://bitcoincore.org/en/list/announcements/join/

How to Upgrade

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 (on Windows) or just copy over /Applications/Bitcoin-Qt (on Mac) or bitcoind/bitcoin-qt (on Linux).

The first time you run version 0.15.0 or newer, 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.

Note that the block database format also changed in version 0.8.0 and there is no automatic upgrade code from before version 0.8 to version 0.15.0. Upgrading directly from 0.7.x and earlier without redownloading the blockchain is not supported. However, as usual, old wallet versions are still supported.

Compatibility

Bitcoin Core is supported and extensively tested on operating systems using the Linux kernel, macOS 10.10+, and Windows 7 and newer. It is not recommended to use Bitcoin Core on unsupported systems.

Bitcoin Core should also work on most other Unix-like systems but is not as frequently tested on them.

From 0.17.0 onwards, macOS <10.10 is no longer supported. 0.17.0 is built using Qt 5.9.x, which doesn't support versions of macOS older than 10.10. Additionally, Bitcoin Core does not yet change appearance when macOS "dark mode" is activated.

In addition to previously-supported CPU platforms, this release's pre-compiled distribution also provides binaries for the RISC-V platform.

Notable changes

Mining

• Calls to getblocktemplate will fail if the segwit rule is not specified. Calling getblocktemplate without segwit specified is almost certainly a misconfiguration since doing so results in lower rewards for the miner. Failed calls will produce an error message describing how to enable the segwit rule.

Configuration option changes

• A warning is printed if an unrecognized section name is used in the configuration file. Recognized sections are [test], [main], and [regtest].

• Four new options are available for configuring the maximum number of messages that ZMQ will queue in memory (the "high water mark") before dropping additional messages. The default value is 1,000, the same as was used for previous releases. See the ZMQ documentation for details.

• The rpcallowip option can no longer be used to automatically listen on all network interfaces. Instead, the rpcbind parameter must also be used to specify the IP addresses to listen on. Listening for RPC commands over a public network connection is insecure and should be disabled, so a warning is now printed if a user selects such a configuration. If you need to expose RPC in order to use a tool like Docker, ensure you only bind RPC to your localhost, e.g. docker run [...] -p 127.0.0.1:8332:8332 (this is an extra :8332 over the normal Docker port specification).

• The rpcpassword option now causes a startup error if the password set in the configuration file contains a hash character (#), as it's ambiguous whether the hash character is meant for the password or as a comment.

• The whitelistforcerelay option is used to relay transactions from whitelisted peers even when not accepted to the mempool. This option now defaults to being off, so that changes in policy and disconnect/ban behavior will not cause a node that is whitelisting another to be dropped by peers. Users can still explicitly enable this behavior with the command line option (and may want to consider contacting the Bitcoin Core project to let us know about their use-case, as this feature could be deprecated in the future).

Documentation

• A new short document about the JSON-RPC interface describes cases where the results of an RPC might contain inconsistencies between data sourced from different subsystems, such as wallet state and mempool state. A note is added to the REST interface documentation indicating that the same rules apply.

• Further information is added to the JSON-RPC documentation about how to secure this interface.

• A new document about the bitcoin.conf file describes how to use it to configure Bitcoin Core.

• A new document introduces Bitcoin Core's BIP174 Partially-Signed Bitcoin Transactions (PSBT) interface, which is used to allow multiple programs to collaboratively work to create, sign, and broadcast new transactions. This is useful for offline (cold storage) wallets, multisig wallets, coinjoin implementations, and many other cases where two or more programs need to interact to generate a complete transaction.

• The output script descriptor documentation has been updated with information about new features in this still-developing language for describing the output scripts that a wallet or other program wants to receive notifications for, such as which addresses it wants to know received payments. The language is currently used in the scantxoutset RPC and is expected to be adapted to other RPCs and to the underlying wallet structure.

Build system changes

• A new --disable-bip70 option may be passed to ./configure to prevent Bitcoin-Qt from being built with support for the BIP70 payment protocol or from linking libssl. As the payment protocol has exposed Bitcoin Core to libssl vulnerabilities in the past, builders who don't need BIP70 support are encouraged to use this option to reduce their exposure to future vulnerabilities.

Deprecated or removed RPCs

• The signrawtransaction RPC is removed after being deprecated and hidden behind a special configuration option in version 0.17.0.

• The 'account' API is removed after being deprecated in v0.17. The 'label' API was introduced in v0.17 as a replacement for accounts. See the release notes from v0.17 for a full description of the changes from the 'account' API to the 'label' API.

• The addwitnessaddress RPC is removed after being deprecated in version 0.13.0.

• The wallet's generate RPC method is deprecated and will be fully removed in a subsequent major version. This RPC is only used for testing, but its implementation reached across multiple subsystems (wallet and mining), so it is being deprecated to simplify the wallet-node interface. Projects that are using generate for testing purposes should transition to using the generatetoaddress RPC, which does not require or use the wallet component. Calling generatetoaddress with an address returned by the getnewaddress RPC gives the same functionality as the old generate RPC. To continue using generate in this version, restart bitcoind with the -deprecatedrpc=generate configuration option.

Deprecated P2P messages

• BIP 61 reject messages are now deprecated. Reject messages have no use case on the P2P network and are only logged for debugging by most network nodes. Furthermore, they increase bandwidth and can be harmful for privacy and security. It has been possible to disable BIP 61 messages since v0.17 with the -enablebip61=0 option. BIP 61 messages will be disabled by default in a future version, before being removed entirely.

New RPCs

• The getnodeaddresses RPC returns peer addresses known to this node. It may be used to find nodes to connect to without using a DNS seeder.

• The listwalletdir RPC returns a list of wallets in the wallet directory (either the default wallet directory or the directory configured by the -walletdir parameter).

• The getrpcinfo returns runtime details of the RPC server. At the moment, it returns an array of the currently active commands and how long they've been running.

• deriveaddresses returns one or more addresses corresponding to an output descriptor.

Updated RPCs

Note: some low-level RPC changes mainly useful for testing are described in the Low-level Changes section below.

• The getpeerinfo RPC now returns an additional minfeefilter field set to the peer's BIP133 fee filter. You can use this to detect that you have peers that are willing to accept transactions below the default minimum relay fee.

• The mempool RPCs, such as getrawmempool with verbose=true, now return an additional "bip125-replaceable" value indicating whether the transaction (or its unconfirmed ancestors) opts-in to asking nodes and miners to replace it with a higher-feerate transaction spending any of the same inputs.

• The settxfee RPC previously silently ignored attempts to set the fee below the allowed minimums. It now prints a warning. The special value of "0" may still be used to request the minimum value.

• The getaddressinfo RPC now provides an ischange field indicating whether the wallet used the address in a change output.

• The importmulti RPC has been updated to support P2WSH, P2WPKH, P2SH-P2WPKH, and P2SH-P2WSH. Requests for P2WSH and P2SH-P2WSH accept an additional witnessscript parameter.

• The importmulti RPC now returns an additional warnings field for each request with an array of strings explaining when fields are being ignored or are inconsistent, if there are any.

• The getaddressinfo RPC now returns an additional solvable boolean field when Bitcoin Core knows enough about the address's scriptPubKey, optional redeemScript, and optional witnessScript in order for the wallet to be able to generate an unsigned input spending funds sent to that address.

• The getaddressinfo, listunspent, and scantxoutset RPCs now return an additional desc field that contains an output descriptor containing all key paths and signing information for the address (except for the private key). The desc field is only returned for getaddressinfo and listunspent when the address is solvable.

• The importprivkey RPC will preserve previously-set labels for addresses or public keys corresponding to the private key being imported. For example, if you imported a watch-only address with the label "cold wallet" in earlier releases of Bitcoin Core, subsequently importing the private key would default to resetting the address's label to the default empty-string label (""). In this release, the previous label of "cold wallet" will be retained. If you optionally specify any label besides the default when calling importprivkey, the new label will be applied to the address.

• See the Mining section for changes to getblocktemplate.

• The getmininginfo RPC now omits currentblockweight and currentblocktx when a block was never assembled via RPC on this node.

• The getrawtransaction RPC & REST endpoints no longer check the unspent UTXO set for a transaction. The remaining behaviors are as follows: 1. If a blockhash is provided, check the corresponding block. 2. If no blockhash is provided, check the mempool. 3. If no blockhash is provided but txindex is enabled, also check txindex.

• The unloadwallet RPC is now synchronous, meaning it will not return until the wallet is fully unloaded.

• The importmulti RPC now supports importing of addresses from descriptors. A "desc" parameter can be provided instead of the "scriptPubKey" in a request, as well as an optional range for ranged descriptors to specify the start and end of the range to import. More information about descriptors can be found here.

• The listunspent RPC has been modified so that it also returns witnessScript, the witness script in the case of a P2WSH or P2SH-P2WSH output.

• The RPC createwallet now has an optional blank argument that can be used to create a blank wallet. Blank wallets do not have any keys or HD seed. They cannot be opened in software older than 0.18. Once a blank wallet has a HD seed set (by using sethdseed) or private keys, scripts, addresses, and other watch only things have been imported, the wallet is no longer blank and can be opened in 0.17.x. Encrypting a blank wallet will also set a HD seed for it.

REST changes

• A new /rest/blockhashbyheight/ endpoint is added for fetching the hash of the block in the current best blockchain based on its height (how many blocks it is after the Genesis Block).

Graphical User Interface (GUI)

• A new Window menu is added alongside the existing File, Settings, and Help menus. Several items from the other menus that opened new windows have been moved to this new Window menu.

• In the Send tab, the checkbox for "pay only the required fee" has been removed. Instead, the user can simply decrease the value in the Custom Feerate field all the way down to the node's configured minimum relay fee.

• In the Overview tab, the watch-only balance will be the only balance shown if the wallet was created using the createwallet RPC and the disable_private_keys parameter was set to true.

• The launch-on-startup option is no longer available on macOS if compiled with macosx min version greater than 10.11 (use CXXFLAGS="-mmacosx-version-min=10.11" CFLAGS="-mmacosx-version-min=10.11" for setting the deployment sdk version)

Tools

• A new bitcoin-wallet tool is now distributed alongside Bitcoin Core's other executables. Without needing to use any RPCs, this tool can currently create a new wallet file or display some basic information about an existing wallet, such as whether the wallet is encrypted, whether it uses an HD seed, how many transactions it contains, and how many address book entries it has.

Dependencies

• The minimum required version of QT (when building the GUI) has been increased from 5.2 to 5.5.1 (the depends system provides 5.9.7)

Low-level changes

RPC

• The submitblock RPC previously returned the reason a rejected block was invalid the first time it processed that block but returned a generic "duplicate" rejection message on subsequent occasions it processed the same block. It now always returns the fundamental reason for rejecting an invalid block and only returns "duplicate" for valid blocks it has already accepted.

• A new submitheader RPC allows submitting block headers independently from their block. This is likely only useful for testing.

• The signrawtransactionwithkey and signrawtransactionwithwallet RPCs have been modified so that they also optionally accept a witnessScript, the witness script in the case of a P2WSH or P2SH-P2WSH output. This is compatible with the change to listunspent.

• Descriptors with key origin information imported through importmulti will have their key origin information stored in the wallet for use with creating PSBTs.

• If bip32derivs of both walletprocesspsbt and walletcreatefundedpsbt is set to true but the key metadata for a public key has not been updated yet, then that key will have a derivation path as if it were just an independent key (i.e. no derivation path and its master fingerprint is itself)

Configuration

• The -usehd configuration option was removed in version 0.16. From that version onwards, all new wallets created are hierarchical deterministic wallets. This release makes specifying -usehd an invalid configuration option.

Network

• This release allows peers that your node automatically disconnected for misbehavior (e.g. sending invalid data) to reconnect to your node if you have unused incoming connection slots. If your slots fill up, a misbehaving node will be disconnected to make room for nodes without a history of problems (unless the misbehaving node helps your node in some other way, such as by connecting to a part of the Internet from which you don't have many other peers). Previously, Bitcoin Core banned the IP addresses of misbehaving peers for a period of time (default of 1 day); this was easily circumvented by attackers with multiple IP addresses. If you manually ban a peer, such as by using the setban RPC, all connections from that peer will still be rejected.

Wallet

• The key metadata will need to be upgraded the first time that the HD seed is available. For unencrypted wallets this will occur on wallet loading. For encrypted wallets this will occur the first time the wallet is unlocked.

Security

• This release changes the Random Number Generator (RNG) used from OpenSSL to Bitcoin Core's own implementation, although entropy gathered by Bitcoin Core is fed out to OpenSSL and then read back in when the program needs strong randomness. This moves Bitcoin Core a little closer to no longer needing to depend on OpenSSL, a dependency that has caused security issues in the past.

Changes for particular platforms

• On macOS, Bitcoin Core now opts out of application CPU throttling ("app nap") during initial blockchain download, when catching up from over 100 blocks behind the current chain tip, or when reindexing chain data. This helps prevent these operations from taking an excessively long time because the operating system is attempting to conserve power.

Credits

Thanks to everyone who directly contributed to this release:

As well as everyone that helped translating on Transifex.