26.0 Release Notes

Bitcoin Core version 26.0 is now available from:

<https://bitcoincore.org/bin/bitcoin-core-26.0/>

P2P and network changes

- Experimental support for the v2 transport protocol defined in

[BIP324](https://github.com/bitcoin/bips/blob/master/bip-0324.mediawiki) was added.

It is off by default, but when enabled using `-v2transport` it will be negotiated

on a per-connection basis with other peers that support it too. The existing

v1 transport protocol remains fully supported.

- 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. (#27213)

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. (#27596)

Updated RPCs

- 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. (#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 It is superseded by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. (#28685)

- 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.

- A new argument `v2transport` was added to the `addnode` RPC to indicate whether a v2 transaction connection

is to be attempted with the peer.

- [Miniscript](https://bitcoin.sipa.be/miniscript/) expressions can now be used in Taproot descriptors for all RPCs working with descriptors. (#27255)

- `finalizepsbt` is now able to finalize a PSBT with inputs spending [Miniscript](https://bitcoin.sipa.be/miniscript/)-compatible Taproot leaves. (#27255)

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. UTXO snapshot are typically obtained via

third-party sources (HTTP, torrent, etc.) which is reasonable since their contents

are always checked by hash.

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 `getprioritisedtransactions` RPC has been added. It returns a map of all fee deltas created by the

user with prioritisetransaction, indexed by txid. The map also indicates whether each transaction is

present in the mempool. (#27501)

- 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). (#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 RPC `getaddrmaninfo` has been added to view the distribution of addresses in the new and tried table of the

node's address manager across different networks(ipv4, ipv6, onion, i2p, cjdns). The RPC returns count of addresses

in new and tried table as well as their sum for all networks. (#27511)

- 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. (#27460)

- Warning: Importing untrusted files is dangerous, especially if metadata from the file is taken over.

- If you want to apply fee deltas, it is recommended to use the `getprioritisedtransactions` and

`prioritisetransaction` RPCs instead of the `apply_fee_delta_priority` option to avoid

double-prioritising any already-prioritised transactions in the mempool.

Updated settings

- `bitcoind` and `bitcoin-qt` will now raise an error on startup

if a datadir that is being used contains a bitcoin.conf file that

will be ignored, which can happen when a datadir= line is used in

a bitcoin.conf file. The error message is just a diagnostic intended

to prevent accidental misconfiguration, and it can be disabled to

restore the previous behavior of using the datadir while ignoring

the bitcoin.conf contained in it. (#27302)

- Passing an invalid `-debug`, `-debugexclude`, or `-loglevel` logging configuration

option now raises an error, rather than logging an easily missed warning. (#27632)

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

New settings

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.

- A new `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_TAPROOT` flag is available in libconsensus that will verify scripts with the Taproot spending rules.

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. (#24914)

- The `gettransaction`, `listtransactions`, `listsinceblock` RPCs now return

the `abandoned` field for all transactions. Previously, the "abandoned" field

was only returned for sent transactions. (#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. (#26076)

- The `getbalances` RPC now returns a `lastprocessedblock` JSON object which contains the wallet's last processed block

hash and height at the time the balances were calculated. This result shouldn't be cached because importing new keys could invalidate it. (#26094)

- The `gettransaction` RPC now returns a `lastprocessedblock` JSON object which contains the wallet's last processed block

hash and height at the time the transaction information was generated. (#26094)

- The `getwalletinfo` RPC now returns a `lastprocessedblock` JSON object which contains the wallet's last processed block

hash and height at the time the wallet information was generated. (#26094)

- 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. (#26152)

- For RPC methods which accept `options` parameters ((`importmulti`, `listunspent`,

`fundrawtransaction`, `bumpfee`, `send`, `sendall`, `walletcreatefundedpsbt`,

`simulaterawtransaction`), it is now possible to pass the options as named

parameters without the need for a nested object. (#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}'

- 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. (#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. (#28113)

- RPC `walletprocesspsbt`, and `descriptorprocesspsbt` return

object now includes field `hex` (if the transaction

is complete) containing the serialized transaction

suitable for RPC `sendrawtransaction`. (#28414)

- It's now possible to use [Miniscript](https://bitcoin.sipa.be/miniscript/) inside Taproot leaves for descriptor wallets. (#27255)

GUI changes

- The transaction list in the GUI no longer provides a special category for "payment to yourself". Now transactions that have both inputs and outputs that affect the wallet are displayed on separate lines for spending and receiving. (gui#119)

- 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)

- The ability to create legacy wallets is being removed. (gui#764)

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`. (#28354)

- 0xb10c

- Amiti Uttarwar

- Andrew Toth

- Anthony Towns

- Antoine Poinsot

- Antoine Riard

- Ari

- Aurèle Oulès

- Ayush Singh

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- Brotcrunsher

- brunoerg

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- Carl Dong

- Casey Carter

- Cory Fields

- David Álvarez Rosa

- dergoegge

- dhruv

- dimitaracev

- Erik Arvstedt

- Erik McKelvey

- Fabian Jahr

- glozow

- Greg Sanders

- Harris

- Hernan Marino

- ishaanam

- ismaelsadeeq

- Jake Rawsthorne

- James O'Beirne

- John Moffett

- Jon Atack

- josibake

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- Larry Ruane

- Luke Dashjr

- Marnix

- Martin Leitner-Ankerl

- Matthew Zipkin

- Michael Ford

- Michael Tidwell

- mruddy

- ns-xvrn

- pablomartin4btc

- Pieter Wuille

- Reese Russell

- Rhythm Garg

- Ryan Ofsky

- Sebastian Falbesoner

- Sjors Provoost

- stickies-v

- stratospher

- Suhas Daftuar

- TheCharlatan

- Tim Neubauer

- Tim Ruffing

- Vasil Dimov

- virtu

- vuittont60

- willcl-ark

- Yusuf Sahin HAMZA