doc/release-notes/release-notes-27.0.md
Bitcoin Core version 27.0 is now available from:
https://bitcoincore.org/bin/bitcoin-core-27.0/
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/
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.
Bitcoin Core is supported and extensively tested on operating systems using the Linux Kernel 3.17+, macOS 11.0+, and Windows 7 and newer. 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.
libbitcoinconsensus is deprecated and will be removed for v28. This library has existed for nearly 10 years with very little known uptake or impact. It has become a maintenance burden.
The underlying functionality does not change between versions, so any users of the library can continue to use the final release indefinitely, with the understanding that Taproot is its final consensus update.
In the future, libbitcoinkernel will provide a much more useful API that is aware of the UTXO set, and therefore be able to fully validate transactions and blocks. (#29189)
The mempool.dat file created by -persistmempool or the savemempool RPC will
be written in a new format. This new format includes the XOR'ing of transaction
contents to mitigate issues where external programs (such as anti-virus) attempt
to interpret and potentially modify the file.
This new format can not be read by previous software releases. To allow for a
downgrade, a temporary setting -persistmempoolv1 has been added to fall back
to the legacy format. (#28207)
BIP324 v2 transport is now enabled by default. It remains possible to disable v2
by running with -v2transport=0. (#29347)
Manual connection options (-connect, -addnode and -seednode) will
now follow -v2transport to connect with v2 by default. They will retry with
v1 on failure. (#29058)
Network-adjusted time has been removed from consensus code. It is replaced with (unadjusted) system time. The warning for a large median time offset (70 minutes or more) is kept. This removes the implicit security assumption of requiring an honest majority of outbound peers, and increases the importance of the node operator ensuring their system time is (and stays) correct to not fall out of consensus with the network. (#28956)
-acceptnonstdtxn=1 is set. By setting the transaction version number to 3, TRUC transactions
request the application of limits on spending of their unconfirmed outputs. These
restrictions simplify the assessment of incentive compatibility of accepting or
replacing TRUC transactions, thus ensuring any replacements are more profitable for
the node and making fee-bumping more reliable. TRUC transactions are currently
nonstandard and can only be used on test networks where the standardness rules are
relaxed or disabled (e.g. with -acceptnonstdtxn=1). (#28948)-v2transport option (now on by default, see above) for making connections.
It remains possible to specify the transport type manually with the v2transport argument of addnode. (#29239)-consolidatefeerate×3). (#27877)settings.json files. (#29144)Thanks to everyone who directly contributed to this release:
As well as to everyone that helped with translations on Transifex.