READ THE CODE

Inside Bitcoin

The code behind the network, with room to understand it.

Stable release v32.1bitcoin/bitcoin · f0de87f04062 ↗3,020 source files · 47.5 MB stored on the server440 file guides

Release published 2026-10-28 · Snapshot fetched 2026-11-01. Latest stable release at fetch time; development branches and Git history are excluded. Only the selected code window and visible folders load here.

7,811 bytes · SHA-256 877d8f56c8364f67… · View upstream ↗

1Bitcoin Core version 0.12.1 is now available from:
2
3  <https://bitcoin.org/bin/bitcoin-core-0.12.1/>
4
5This is a new minor version release, including the BIP9, BIP68 and BIP112
6softfork, various bugfixes and updated translations.
7
8Please report bugs using the issue tracker at github:
9
10  <https://github.com/bitcoin/bitcoin/issues>
11
12Upgrading and downgrading
13=========================
14
15How to Upgrade
16--------------
17
18If you are running an older version, shut it down. Wait until it has completely
19shut down (which might take a few minutes for older versions), then run the
20installer (on Windows) or just copy over /Applications/Bitcoin-Qt (on Mac) or
21bitcoind/bitcoin-qt (on Linux).
22
23Downgrade warning
24-----------------
25
26### Downgrade to a version < 0.12.0
27
28Because release 0.12.0 and later will obfuscate the chainstate on every
29fresh sync or reindex, the chainstate is not backwards-compatible with
30pre-0.12 versions of Bitcoin Core or other software.
31
32If you want to downgrade after you have done a reindex with 0.12.0 or later,
33you will need to reindex when you first start Bitcoin Core version 0.11 or
34earlier.
35
36Notable changes
37===============
38
39First version bits BIP9 softfork deployment
40-------------------------------------------
41
42This release includes a soft fork deployment to enforce [BIP68][],
43[BIP112][] and [BIP113][] using the [BIP9][] deployment mechanism.
44
45The deployment sets the block version number to 0x20000001 between
46midnight 1st May 2016 and midnight 1st May 2017 to signal readiness for 
47deployment. The version number consists of 0x20000000 to indicate version
48bits together with setting bit 0 to indicate support for this combined
49deployment, shown as "csv" in the `getblockchaininfo` RPC call.
50
51For more information about the soft forking change, please see
52<https://github.com/bitcoin/bitcoin/pull/7648>
53
54This specific backport pull-request can be viewed at
55<https://github.com/bitcoin/bitcoin/pull/7543>
56
57[BIP9]: https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki
58[BIP68]: https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki
59[BIP112]: https://github.com/bitcoin/bips/blob/master/bip-0112.mediawiki
60[BIP113]: https://github.com/bitcoin/bips/blob/master/bip-0113.mediawiki
61
62BIP68 soft fork to enforce sequence locks for relative locktime
63---------------------------------------------------------------
64
65[BIP68][] introduces relative lock-time consensus-enforced semantics of
66the sequence number field to enable a signed transaction input to remain
67invalid for a defined period of time after confirmation of its corresponding
68outpoint.
69
70For more information about the implementation, see
71<https://github.com/bitcoin/bitcoin/pull/7184>
72
73BIP112 soft fork to enforce OP_CHECKSEQUENCEVERIFY
74--------------------------------------------------
75
76[BIP112][] redefines the existing OP_NOP3 as OP_CHECKSEQUENCEVERIFY (CSV)
77for a new opcode in the Bitcoin scripting system that in combination with
78[BIP68][] allows execution pathways of a script to be restricted based
79on the age of the output being spent.
80
81For more information about the implementation, see
82<https://github.com/bitcoin/bitcoin/pull/7524>
83
84BIP113 locktime enforcement soft fork
85-------------------------------------
86
87Bitcoin Core 0.11.2 previously introduced mempool-only locktime
88enforcement using GetMedianTimePast(). This release seeks to
89consensus enforce the rule.
90
91Bitcoin transactions currently may specify a locktime indicating when
92they may be added to a valid block.  Current consensus rules require
93that blocks have a block header time greater than the locktime specified
94in any transaction in that block.
95
96Miners get to choose what time they use for their header time, with the
97consensus rule being that no node will accept a block whose time is more
98than two hours in the future.  This creates a incentive for miners to
99set their header times to future values in order to include locktimed
100transactions which weren't supposed to be included for up to two more
101hours.
102
103The consensus rules also specify that valid blocks may have a header
104time greater than that of the median of the 11 previous blocks.  This
105GetMedianTimePast() time has a key feature we generally associate with
106time: it can't go backwards.
107
108[BIP113][] specifies a soft fork enforced in this release that
109weakens this perverse incentive for individual miners to use a future
110time by requiring that valid blocks have a computed GetMedianTimePast()
111greater than the locktime specified in any transaction in that block.
112
113Mempool inclusion rules currently require transactions to be valid for
114immediate inclusion in a block in order to be accepted into the mempool.
115This release begins applying the BIP113 rule to received transactions,
116so transaction whose time is greater than the GetMedianTimePast() will
117no longer be accepted into the mempool.
118
119**Implication for miners:** you will begin rejecting transactions that
120would not be valid under BIP113, which will prevent you from producing
121invalid blocks when BIP113 is enforced on the network. Any
122transactions which are valid under the current rules but not yet valid
123under the BIP113 rules will either be mined by other miners or delayed
124until they are valid under BIP113. Note, however, that time-based
125locktime transactions are more or less unseen on the network currently.
126
127**Implication for users:** GetMedianTimePast() always trails behind the
128current time, so a transaction locktime set to the present time will be
129rejected by nodes running this release until the median time moves
130forward. To compensate, subtract one hour (3,600 seconds) from your
131locktimes to allow those transactions to be included in mempools at
132approximately the expected time.
133
134For more information about the implementation, see
135<https://github.com/bitcoin/bitcoin/pull/6566>
136
137Miscellaneous
138-------------
139
140The p2p alert system is off by default. To turn on, use `-alert` with
141startup configuration.
142
1430.12.1 Change log
144=================
145
146Detailed release notes follow. This overview includes changes that affect
147behavior, not code moves, refactors and string updates. For convenience in locating
148the code changes and accompanying discussion, both the pull request and
149git merge commit are mentioned.
150
151### RPC and other APIs
152- #7739 `7ffc2bd` Add abandoned status to listtransactions (jonasschnelli)
153
154### Block and transaction handling
155- #7543 `834aaef` Backport BIP9, BIP68 and BIP112 with softfork (btcdrak)
156
157### P2P protocol and network code
158- #7804 `90f1d24` Track block download times per individual block (sipa)
159- #7832 `4c3a00d` Reduce block timeout to 10 minutes (laanwj)
160
161### Validation
162- #7821 `4226aac` init: allow shutdown during 'Activating best chain...' (laanwj)
163- #7835 `46898e7` Version 2 transactions remain non-standard until CSV activates (sdaftuar)
164
165### Build system
166- #7487 `00d57b4` Workaround Travis-side CI issues (luke-jr)
167- #7606 `a10da9a` No need to set -L and --location for curl (MarcoFalke)
168- #7614 `ca8f160` Add curl to packages (now needed for depends) (luke-jr)
169- #7776 `a784675` Remove unnecessary executables from gitian release (laanwj)
170
171### Wallet
172- #7715 `19866c1` Fix calculation of balances and available coins. (morcos)
173
174### Miscellaneous
175- #7617 `f04f4fd` Fix markdown syntax and line terminate LogPrint (MarcoFalke)
176- #7747 `4d035bc` added depends cross compile info (accraze)
177- #7741 `a0cea89` Mark p2p alert system as deprecated (btcdrak)
178- #7780 `c5f94f6` Disable bad-chain alert (btcdrak)
179
180Credits
181=======
182
183Thanks to everyone who directly contributed to this release:
184
185- accraze
186- Alex Morcos
187- BtcDrak
188- Jonas Schnelli
189- Luke Dashjr
190- MarcoFalke
191- Mark Friedenbach
192- NicolasDorier
193- Pieter Wuille
194- Suhas Daftuar
195- Wladimir J. van der Laan
196
197As well as everyone that helped translating on [Transifex](https://www.transifex.com/projects/p/bitcoin/).
198
199

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/init.cpp

src/crypto/sha256.cpp

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/util/chaintype.cpp

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/net_permissions.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/rpc/util.h

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/util/rbf.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/any.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

src/clientversion.cpp

src/common/signmessage.cpp

src/compat/assumptions.h

src/compat/byteswap.h

src/deploymentinfo.cpp

src/deploymentinfo.h

src/deploymentstatus.cpp

src/deploymentstatus.h

src/dummywallet.cpp

src/external_signer.h

src/init/bitcoin-gui.cpp

src/init/bitcoin-node.cpp

src/init/bitcoin-qt.cpp

src/init/bitcoin-wallet.cpp

src/init/bitcoind.cpp

src/init/common.h

src/interfaces/init.h

src/interfaces/ipc.h

src/key_io.h

src/logging/categories.h

src/logging/timer.h

src/mapport.h

src/musig.h

src/net_permissions.h

src/netgroup.h

src/netmessagemaker.h

src/node/chainstatemanager_args.cpp

src/node/connection_types.h

src/node/context.h

src/node/interface_ui.h

src/node/mempool_args.cpp

src/node/mining_args.cpp

src/node/minisketchwrapper.cpp

src/node/txreconciliation.h

src/policy/fees/estimator_args.cpp

src/policy/fees/estimator_args.h

src/policy/fees/estimator_man.cpp

src/policy/fees/estimator_man.h

src/policy/packages.h

src/policy/rbf.h

src/policy/truc_policy.h

src/pow.h

src/primitives/block.cpp

src/randomenv.h

src/rest.h

src/script/keyorigin.h

src/script/parsing.cpp

src/script/parsing.h

src/script/script_error.h

src/script/sigcache.cpp

src/script/sigcache.h

src/script/solver.h

src/script/verify_flags.h

src/semaphore_grant.h

src/signet.h

src/span.h

src/support/allocators/secure.h

src/support/allocators/zeroafterfree.h

src/util/tokenpipe.cpp

src/util/translation.h

src/util/vector.h

src/versionbits.h

src/versionbits_impl.h

src/wallet/external_signer_scriptpubkeyman.h

src/wallet/fees.h

src/wallet/load.h

src/wallet/receive.h

src/wallet/rpc/wallet.h

src/wallet/types.h

src/walletinitinterface.h

src/zmq/zmqabstractnotifier.cpp

Independent explanations by MyBitcoinExplorer. Not affiliated with or endorsed by Bitcoin Core. Guides are educational and do not replace the source or its tests.

Bitcoin Core source © its contributors, distributed under the MIT license. Original notices and bundled third-party licenses are retained in the source tree.