Bitcoin Core v31.0 Released

v31.0 Release Notes

Bitcoin Core version 31.0 is now available from:

https://bitcoincore.org/bin/bitcoin-core-31.0/

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/bitcoin/bitcoin/issues

To receive security and update notifications, please subscribe to:

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

With the release of this new major version, versions 28.x and
older are at "End of Life" and will no longer receive updates.

In accordance with the security policy, we will in two weeks disclose:

Medium and high severity vulnerabilities fixed in 29.0. There is one of these.
Low severity vulnerabilities fixed in 31.0. There are none of these.

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 a version of Bitcoin Core that has reached its EOL is
possible, but it might take some time if the data directory needs to be
migrated. Old wallet versions of Bitcoin Core are generally supported.

Compatibility

Bitcoin Core is supported and tested on the following operating systems or
newer: Linux Kernel 3.17, macOS 14, and Windows 10 (version 1903). Bitcoin Core
should also work on most other Unix-like systems but is not as frequently tested
on them. It is not recommended to use Bitcoin Core on unsupported systems.

Notable changes

The default -dbcache value has been increased to 1024 MiB from 450 MiB on
systems where at least 4096 MiB of RAM is detected. This improves performance
but increases memory usage. On some systems (for example when running in
containers), the detected RAM may exceed the memory actually available, which
can lead to out-of-memory conditions. To maintain the previous behavior, set
-dbcache=450. See
reduce-memory.md
for further guidance on low-memory systems. (#34692)

Mempool

The mempool has been reimplemented with a new design ("cluster mempool"), to
facilitate better decision-making when constructing block templates, evicting
transactions, relaying transactions, and validating replacement transactions
(RBF). Most changes should be transparent to users, but some behavior changes
are noted:

The mempool no longer enforces ancestor or descendant size/count limits.
Instead, two new default policy limits are introduced governing connected
components, or clusters, in the mempool, limiting clusters to 64 transactions
and up to 101 kB in virtual size. Transactions are considered to be in the same
cluster if they are connected to each other via any combination of parent/child
relationships in the mempool. These limits can be overridden using command-line
arguments; see the extended help (-help-debug) for more information.
Within the mempool, transactions are ordered based on the feerate at which
they are expected to be mined, which takes into account the full set, or
"chunk", of transactions that would be included together (e.g., a parent and its
child, or more complicated subsets of transactions). This ordering is utilized
by the algorithms that implement transaction selection for constructing block
templates; eviction from the mempool when it is full; and transaction relay
announcements to peers.
The replace-by-fee validation logic has been updated so that transaction
replacements are only accepted if the resulting mempool's feerate diagram is
strictly better than before the replacement. This eliminates all known cases of
replacements occurring that make the mempool worse off, which was possible under
previous RBF rules. For singleton transactions (that are in clusters by
themselves) it's sufficient for a replacement to have a higher fee and feerate
than the original. See delvingbitcoin.org
post
for more information.
Two new RPCs have been added: getmempoolcluster will provide the set of
transactions in the same cluster as the given transaction, along with the
ordering of those transactions and grouping into chunks; and
getmempoolfeeratediagram will return the feerate diagram of the entire
mempool.
Chunk size and chunk fees are now also included in the output of
getmempoolentry.
The "CPFP Carveout" has been removed from the mempool logic. The CPFP carveout
allowed one additional child transaction to be added to a package that's already
at its descendant limit, but only if that child has exactly one ancestor (the
package's root) and is small (no larger than 10kvB). Nothing is allowed to
bypass the cluster count limit. It is expected that smart contracting use-cases
requiring similar functionality employ TRUC transactions and sibling eviction
instead going forward.
Some additional discussion can be found at
doc/policy/mempool-terminology.md
and
doc/policy/mempool-replacements.md.

P2P and network changes

Normally local transactions are broadcast to all connected peers with which we
do transaction relay. Now, for the sendrawtransaction RPC this behavior can be
changed to only do the broadcast via the Tor or I2P networks. A new boolean
option -privatebroadcast has been added to enable this behavior. This improves
the privacy of the transaction originator in two aspects:
<ol>
- Their IP address (and thus geolocation) is never known to the recipients.
- If the originator sends two otherwise unrelated transactions, they will not
  be linkable. This is because a separate connection is used for broadcasting
  each transaction. (#29415)
</ol>
New RPCs have been added to introspect and control private broadcast:
getprivatebroadcastinfo reports transactions currently being privately
broadcast, and abortprivatebroadcast removes matching transactions from the
private broadcast queue. (#34329)
Transactions participating in one-parent-one-child package relay can now have
the parent with a feerate lower than the -minrelaytxfee feerate, even 0 fee.
This expands the change from 28.0 to also cover packages of non-TRUC
transactions. Note that in general the package child can have additional
unconfirmed parents, but they must already be in-mempool for the new package to
be relayed. (#33892)
The release has asmap data embedded for the first time, allowing the asmap
feature to be used without any externally sourced file. The embedded map was
created on 2026-03-05. Despite
the data being available, the option remains off-by-default. Users still need to
set -asmap or -asmap=1 explicitly to make it possible to use a peer's ASN
(ISP/hoster identifier) in netgroup bucketing in order to ensure a higher
diversity in their peer set.

Updated RPCs

gettxspendingprevout has 2 new optional arguments: mempool_only and
return_spending_tx. If mempool_only is true it will limit scans to the
mempool even if txospenderindex is available. If return_spending_tx is true,
the full spending tx will be returned. In addition if txospenderindex is
available and a confirmed spending transaction is found, its block hash will be
returned. (#24539)
The getpeerinfo RPC no longer returns the startingheight field unless the
configuration option -deprecatedrpc=startingheight is used. The
startingheight field will be fully removed in the next major release. (#34197)
The getblock RPC now returns a coinbase_tx object at verbosity levels 1,
2, and 3. It contains version, locktime, sequence, coinbase and
witness. This allows for efficiently querying coinbase transaction properties
without fetching the full transaction data at verbosity 2+. (#34512)

REST API

A new REST API endpoint
(/rest/blockpart/<BLOCK-HASH>.<bin|hex>?offset=<OFFSET>&size=<SIZE>) has been
introduced for efficiently fetching a range of bytes from block <BLOCK-HASH>.
(#33657)

Build System

The minimum supported Clang compiler version has been raised to 17.0 (#33555).
The minimum supported GCC compiler version has been raised to 12.1 (#33842).

Updated settings

The -paytxfee startup option and the settxfee RPC are now deleted after
being deprecated in Bitcoin Core 30.0. They used to allow the user to set a
static fee rate for wallet transactions, which could potentially lead to
overpaying or underpaying. Users should instead rely on fee estimation or
specify a fee rate per transaction using the fee_rate argument in RPCs such as
fundrawtransaction, sendtoaddress, send, sendall, and sendmany.
(#32138)
Specifying -asmap or -asmap=1 will load the embedded asmap data instead of
an external file. In previous releases, if -asmap was specified without a
filename, this would try to load an ip_asn.map data file. Now loading an
external asmap file always requires an explicit filename like
-asmap=ip_asn.map.
The -maxorphantx startup option has been removed. It was previously
deprecated and has no effect anymore since v30.0. (#33872)
tor has been removed as a network specification. It was deprecated in favour
of onion in v0.17.0. (#34031)
When -logsourcelocations is enabled, the log output now contains just the
function name instead of the entire function signature. (#34088)
The default -dbcache value has been increased to 1024 MiB from 450 MiB
on systems where at least 4096 MiB of RAM is detected. This is a performance
increase, but will use more memory. To maintain the previous behaviour, set
-dbcache=450. (#34692)
-privatebroadcast is added to enable private broadcast behavior for
sendrawtransaction.

New settings

-txospenderindex enables the creation of a transaction output spender index
that, if present, will be scanned by gettxspendingprevout if a spending
transaction was not found in the mempool. (#24539)

GUI changes

The GUI has been updated to Qt 6.8. (#34650)
The createwallet, createwalletdescriptor and migratewallet commands are
filtered from the console history to improve security and privacy. (gui#901)
The Restore Wallet dialog shows an error message if the restored wallet name
is empty. (gui#924)

Fee Estimation

The Bitcoin Core fee estimator minimum fee rate bucket was updated from <strong>1
sat/vB</strong> to <strong>0.1 sat/vB</strong>, which matches the node’s default minrelaytxfee. This
means that for a given confirmation target, if a sub-1 sat/vB fee rate bucket is
the minimum tracked with sufficient data, its average value will be returned as
the fee rate estimate.

Restarting a node with this change invalidates previously saved
estimates in fee_estimates.dat, the fee estimator will start tracking fresh
stats.

IPC Interface

The IPC mining interface now requires mining clients to use the latest
mining.capnp schema. Clients built against older schemas will fail when
calling Init.makeMining and receive an RPC error indicating the old mining
interface is no longer supported. Mining clients must update to the latest
schema and regenerate bindings to continue working. (#34568)
Mining.createNewBlock now has a cooldown behavior (enabled by default)
that waits for IBD to finish and for the tip to catch up. This usually prevents
a flood of templates during startup, but is not guaranteed. (#34184)
Mining.interrupt() can be used to interrupt Mining.waitTipChanged and
Mining.createNewBlock. (#34184)
Mining.createNewBlock and Mining.checkBlock now require a context
parameter.
Mining.waitTipChanged now has a default timeout (effectively infinite /
maxDouble) if the client omits it.
BlockTemplate.getCoinbaseTx() now returns a structured CoinbaseTx instead
of raw bytes.
Removed BlockTemplate.getCoinbaseCommitment() and
BlockTemplate.getWitnessCommitmentIndex().
Cap’n Proto default values were updated to match the corresponding C++
defaults for mining-related option structs (e.g. BlockCreateOptions,
BlockWaitOptions, BlockCheckOptions).

Credits

Thanks to everyone who directly contributed to this release:

0xb10c
Alexander Wiederin
Alfonso Roman Zubeldia
amisha
ANAVHEOBA
Andrew Toth
Anthony Towns
Antoine Poinsot
ANtutov
Anurag chavan
Ava Chow
bensig
Ben Westgate
billymcbip
b-l-u-e
Brandon Odiwuor
brunoerg
Bruno Garcia
Calin Culianu
Carl Dong
Chandra Pratap
Chris Stewart
Coder
Cory Fields
da1sychain
Daniela Brozzoni
Daniel Pfeifer
David Gumberg
dergoegge
Dmitry Goncharov
Enoch Azariah
Eugene Siegel
Fabian Jahr
fanquake
Fibonacci747
flack
frankomosh
furszy
glozow
Greg Sanders
Hao Xu
Hennadii Stepanov
Henry Romp
Hodlinator
ismaelsadeeq
janb84
jayvaliya
joaonevess
John Moffett
Josh Doman
kevkevinpal
l0rinc
Luke Dashjr
Mara van der Laan
MarcoFalke
marcofleon
Martin Zumsande
Matthew Zipkin
Max Edwards
Murch
Musa Haruna
naiyoma
nervana21
Novo
optout
pablomartin4btc
Padraic Slattery
Pieter Wuille
Pol Espinasa
pythcoiner
rkrux
Robin David
Roman Zeyde
rustaceanrob
Ryan Ofsky
SatsAndSports
scgbckbone
Sebastian Falbesoner
sedited
seduless
Sergi Delgado Segura
Sjors Provoost
SomberNight
sstone
stickies-v
stratospher
stringintech
Suhas Daftuar
tboy1337
TheCharlatan
Tim Ruffing
Vasil Dimov
w0xlt
WakeTrainDev
Weixie Cui
willcl-ark
Woolfgm
yancy
Yash Bhutwala
yuvicc
zaidmstrr

As well as to everyone that helped with translations on
Transifex.

SHA256SUMS:

Code:

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SHA256SUMS.asc

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