26.1 Release Notes

Bitcoin Knots version 26.1.knots20240325 is now available from:

https://bitcoinknots.org/files/26.x/26.1.knots20240325/

This release includes new features, various bug fixes and performance
improvements, as well as updated translations.

Please report bugs using the issue tracker at GitHub:

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

To receive security and update notifications, please subscribe to:

https://bitcoinknots.org/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 in some cases), then run the installer (on Windows) or just copy over /Applications/Bitcoin-Qt (on macOS) or bitcoind/bitcoin-qt (on Linux).

Upgrading directly from very old versions of Bitcoin Core or Knots is possible, but it might take some time if the data directory needs to be migrated. Old wallet versions of Bitcoin Knots are generally supported.

Compatibility

Bitcoin Knots is supported on operating systems using the Linux kernel, macOS 11.0+, and Windows 7 and newer. It is not recommended to use Bitcoin Knots on unsupported systems.

Known Bugs

In various locations, including the GUI's transaction details dialog and the "vsize" result in many RPC results, transaction virtual sizes may not account for an unusually high number of sigops (ie, as determined by the -bytespersigop policy). This could result in reporting a lower virtual size than is actually used for mempool or mining purposes.

In the interest of time, this release does not include updated translations. Please comment on GitHub #73 if this is of particular importance to you or anyone you know. If nobody expresses interest in localization, it may continue to be skipped going forward.

Notable changes

Node policy changes

• Spam is sometimes disguised to appear as if it is a deprecated pay-to-IP (bare pubkey) transaction, where the "key" is actually arbitrary data (not a real key) instead. Due to the nature of this spam, it pollutes not only the blockchain, but also permanently bloats the "UTXO set" all nodes must retain (it cannot be pruned). Real pay-to-IP was only ever supported by Satoshi's early Bitcoin wallet, which has been abandoned since 2011. This version of Bitcoin Knots filters out this kind of spam by default. A new setting, -permitbarepubkey (also available in the GUI), is available for users who desire to relay these. (bitcoin#29309)

• Non-standard datacarrier formats are now filtered out by default. If you wish to re-enable relaying and mining them, you can set -acceptnonstddatacarrier=1

• There is now experimental (and disabled by default) support for dynamically adjusting the "dust" spam filter threshold. It can be enabled in the GUI, or by configuring -dustdynamic=target:N to adjust based on a fee estimate for confirmation within N blocks, or -dustdynamic=mempool:N to adjust based on the worst fee in the best N kvB of your mempool. In either mode, the fee will be adjusted every 15 minutes (the first time not for 15 minutes after startup, in an effort to ensure estimators have sufficient data to work with). Implementation details (including how often adjustment occurs) may be changed in future releases. If you use this feature, please leave a comment about your experience on GitHub: #74

P2P and network changes

• For several years now, miners have been regularly violating the Bitcoin protocol as it pertains to the block version bits, triggering warnings in Bitcoin Knots about softforks that aren't happening. While it would be inappropriate to simply concede a protocol change without community support, it's also confusing for users to see warnings that are inaccurate. To mitigate this, therefore, Bitcoin Knots is now more specific about when it warns about potential protocol changes, and only logs simple versionbit protocol violations in the debug log once for the specific block violating it.

• Support for the v2 transport protocol defined in BIP324 was added. It is on by default and will be negotiated on a per-connection basis with other peers that support it, but can be disabled using -v2transport=0 if desired. The existing v1 transport protocol remains fully supported. (bitcoin#28331)

• Nodes with multiple reachable networks will actively try to have at least one outbound connection to each network. This improves individual resistance to eclipse attacks and network level resistance to partition attacks. Users no longer need to perform active measures to ensure being connected to multiple enabled networks. (bitcoin#27213)

• Support for I2P sessions encrypted using the newer and faster ECIES-X25519 algorithm has been added. (bitcoin#29200)

Pruning

• When using assumeutxo with -prune, the prune budget may be exceeded if it is set lower than 1100MB (i.e. MIN_DISK_SPACE_FOR_BLOCK_FILES * 2). Prune budget is normally split evenly across each chainstate, unless the resulting prune budget per chainstate is beneath MIN_DISK_SPACE_FOR_BLOCK_FILES in which case that value will be used. (bitcoin#27596)

Updated RPCs

• The maxfeerate option for sendrawtransaction and testmempoolaccept is now limited to below 100000 sats/vB to avoid overflow bugs. (bitcoin#29434)

• Setting -rpcserialversion=0 is deprecated and will be removed in a future release. It can currently still be used by also adding the -deprecatedrpc=serialversion option. (bitcoin#28448)

• The hash_serialized_2 value has been removed from gettxoutsetinfo since the value it calculated contained a bug and did not take all data into account. It is superseded by hash_serialized_3 which provides the same functionality but serves the correctly calculated hash. (bitcoin#28685)

• For RPC methods which accept options parameters (importmulti, listunspent, fundrawtransaction, bumpfee, scanblocks, send, sendall, walletcreatefundedpsbt, simulaterawtransaction), it is now possible to pass the options as named parameters without the need for a nested object. (bitcoin#26485)

This means it is possible make calls like:

src/bitcoin-cli -named bumpfee txid fee_rate=100

instead of

src/bitcoin-cli -named bumpfee txid options='{"fee_rate": 100}'

• New fields transport_protocol_type and session_id were added to the getpeerinfo RPC to indicate whether the v2 transport protocol is in use, and if so, what the session id is. (bitcoin#28331)

• A new argument v2transport was added to the addnode RPC to indicate whether a v2 transaction connection is to be attempted with the peer. This breaks compatibility with the old privileged parameter used with Bitcoin Knots v0.16.0.knots20180322 through v0.20.1.knots20200815. If you were relying on this deprecated parameter, you can maintain the previous behaviour by specifying "outbound-full-relay" to the "connection_type" parameter. (bitcoin#28331)

• Miniscript expressions can now be used in Taproot descriptors for all RPCs working with descriptors. (bitcoin#27255)

• finalizepsbt is now able to finalize a PSBT with inputs spending Miniscript-compatible Taproot leaves. (bitcoin#27255)

• The result from getpeerinfo now includes "misbehavior_score". This number is increased (by varying amounts) when a peer doesn't follow the protocol correctly, and when it reaches 100, the peer is disconnected. It is mostly only useful for testing purposes. (bitcoin#29530)

Changes to wallet related RPCs can be found in the Wallet section below.

New RPCs

• loadtxoutset has been added, which allows loading a UTXO snapshot of the format generated by dumptxoutset. Once this snapshot is loaded, its contents will be deserialized into a second chainstate data structure, which is then used to sync to the network's tip.

  Meanwhile, the original chainstate will complete the initial block download process in the background, eventually validating up to the block that the snapshot is based upon.

  The result is a usable bitcoind instance that is current with the network tip in a matter of minutes rather than hours. However, until the full background sync completes, the node and any wallets using it remain insecure and should not be trusted or relied
  on for confirmation of payment. (bitcoin#27596)

  You can find more information on this process in the assumeutxo design document (https://github.com/bitcoin/bitcoin/blob/master/doc/design/assumeutxo.md).

  getchainstates has been added to aid in monitoring the assumeutxo sync process.

• A new RPC, submitpackage, has been added. It can be used to submit a list of raw hex transactions to the mempool to be evaluated as a package using consensus and mempool policy rules. These policies include package CPFP, allowing a child with high fees to bump a parent below the mempool minimum feerate (but not minimum relay feerate). (bitcoin#27609)

  • Warning: successful submission does not mean the transactions will propagate throughout the network, as package relay is not supported.

  • Not all features are available. The package is limited to a child with all of its unconfirmed parents, and no parent may spend the output of another parent. Also, package RBF is not supported. Refer to doc/policy/packages.md for more details on package policies and limitations.

  • This RPC is experimental. Its interface may change.

• A new importmempool RPC has been added. It loads a valid mempool.dat file and attempts to add its contents to the mempool. This can be useful to import mempool data from another node without having to modify the datadir contents and without having to restart the node. (bitcoin#27460)

  • Warning: Importing untrusted files is dangerous, especially if metadata from the file is taken over.
  • Since coin-age priority deltas are stored in a separate mempool-knots.dat file, it is not supported by this new importmempool method.
  • If you want to apply priority deltas, it is recommended to use the getprioritisedtransactions and prioritisetransaction RPCs instead. This supports both coin-age priority and fee deltas.

• listmempooltransactions has been added to efficiently monitor transactions as they are added to the node's mempool, using sequence numbers. (bitcoin#29016)

Updated settings

• Passing an invalid -debug, -debugexclude, or -loglevel logging configuration option now raises an error, rather than logging an easily missed warning. (bitcoin#27632)

Changes to GUI or wallet related settings can be found in the GUI or Wallet section below.

Tools and Utilities

• A new bitcoinconsensus_verify_script_with_spent_outputs function is available in libconsensus which optionally accepts the spent outputs of the transaction being verified. (bitcoin#28539)
• A new bitcoinconsensus_SCRIPT_FLAGS_VERIFY_TAPROOT flag is available in libconsensus that will verify scripts with the Taproot spending rules. (bitcoin#28539)
• bitcoin-tx's replacable option is now optional. If omitted, inputs will be created opting into Replace-By-Fee. (bitcoin#29022)

Wallet

• Wallet loading has changed in this release. Wallets with some corrupted records that could be previously loaded (with warnings) may no longer load. For example, wallets with corrupted address book entries may no longer load. If this happens, it is recommended load the wallet in a previous version of Bitcoin Core and import the data into a new wallet.
  Please also report an issue to help improve the software and make wallet loading more robust in these cases. (bitcoin#24914)

• The gettransaction, listtransactions, listsinceblock RPCs now return the abandoned field for all transactions. Previously, the "abandoned" field was only returned for sent transactions. (bitcoin#25158)

• The listdescriptors, decodepsbt and similar RPC methods now show h rather than apostrophe (') to indicate hardened derivation. This does not apply when using the private parameter, which matches the marker used when descriptor was generated or imported. Newly created wallets use h. This change makes it easier to handle descriptor strings manually. E.g. the importdescriptors RPC call is easiest to use h as the marker: '["desc": ".../0h/..."]'. With this change listdescriptors will use h, so you can copy-paste the result, without having to add escape characters or switch ' to 'h' manually. Note that this changes the descriptor checksum. For legacy wallets the hdkeypath field in getaddressinfo is unchanged, nor is the serialization format of wallet dumps. (bitcoin#26076)

• Coin selection and transaction building now accounts for unconfirmed low-feerate ancestor transactions. When it is necessary to spend unconfirmed outputs, the wallet will add fees to ensure that the new transaction with its ancestors will achieve a mining score equal to the feerate requested by the user. (bitcoin#26152)

• The deprecatedrpc=walletwarningfield configuration option has been removed. The createwallet, loadwallet, restorewallet and unloadwallet RPCs no longer return the "warning" string field. The same information is provided through the "warnings" field added in v25.0, which returns a JSON array of strings. The "warning" string field was deprecated also in v25.0. (bitcoin#27757)

• The signrawtransactionwithkey, signrawtransactionwithwallet, walletprocesspsbt and descriptorprocesspsbt calls now return the more specific RPC_INVALID_PARAMETER error instead of RPC_MISC_ERROR if their sighashtype argument is malformed. (bitcoin#28113)

• It's now possible to use Miniscript inside Taproot leaves for descriptor wallets. (bitcoin#27255)

• If send or sendall methods are used with the locktime parameter is omitted, the wallet will automatically populate it with an appropriate value to deter fee sniping. (bitcoin#28944)

GUI changes

• A new menu option allows migrating a legacy wallet based on keys and implied output script types stored in BerkeleyDB (BDB) to a modern wallet that uses descriptors stored in SQLite. (gui#738)

• The PSBT operations dialog marks outputs paying your own wallet with "own address". (gui#740)

Low-level changes

Tests

• Non-standard transactions are now disabled by default on testnet for relay and mempool acceptance. The previous behaviour can be re-enabled by setting -acceptnonstdtxn=1. (bitcoin#28354)