Inside Bitcoin

126.0 Release Notes
2==================
3
4Bitcoin Core version 26.0 is now available from:
5
6  <https://bitcoincore.org/bin/bitcoin-core-26.0/>
7
8This release includes new features, various bug fixes and performance
9improvements, as well as updated translations.
10
11Please report bugs using the issue tracker at GitHub:
12
13  <https://github.com/bitcoin/bitcoin/issues>
14
15To receive security and update notifications, please subscribe to:
16
17  <https://bitcoincore.org/en/list/announcements/join/>
18
19How to Upgrade
20==============
21
22If you are running an older version, shut it down. Wait until it has completely
23shut down (which might take a few minutes in some cases), then run the
24installer (on Windows) or just copy over `/Applications/Bitcoin-Qt` (on macOS)
25or `bitcoind`/`bitcoin-qt` (on Linux).
26
27Upgrading directly from a version of Bitcoin Core that has reached its EOL is
28possible, but it might take some time if the data directory needs to be migrated. Old
29wallet versions of Bitcoin Core are generally supported.
30
31Compatibility
32==============
33
34Bitcoin Core is supported and extensively tested on operating systems
35using the Linux kernel, macOS 11.0+, and Windows 7 and newer.  Bitcoin
36Core should also work on most other Unix-like systems but is not as
37frequently tested on them.  It is not recommended to use Bitcoin Core on
38unsupported systems.
39
40Notable changes
41===============
42
43P2P and network changes
44-----------------------
45
46- Experimental support for the v2 transport protocol defined in
47  [BIP324](https://github.com/bitcoin/bips/blob/master/bip-0324.mediawiki) was added.
48  It is off by default, but when enabled using `-v2transport` it will be negotiated
49  on a per-connection basis with other peers that support it too. The existing
50  v1 transport protocol remains fully supported.
51
52- Nodes with multiple reachable networks will actively try to have at least one
53  outbound connection to each network. This improves individual resistance to
54  eclipse attacks and network level resistance to partition attacks. Users no
55  longer need to perform active measures to ensure being connected to multiple
56  enabled networks. (#27213)
57
58Pruning
59-------
60
61- When using assumeutxo with `-prune`, the prune budget may be exceeded if it is set
62  lower than 1100MB (i.e. `MIN_DISK_SPACE_FOR_BLOCK_FILES * 2`). Prune budget is normally
63  split evenly across each chainstate, unless the resulting prune budget per chainstate
64  is beneath `MIN_DISK_SPACE_FOR_BLOCK_FILES` in which case that value will be used. (#27596)
65
66Updated RPCs
67------------
68
69- Setting `-rpcserialversion=0` is deprecated and will be removed in
70  a future release. It can currently still be used by also adding
71  the `-deprecatedrpc=serialversion` option. (#28448)
72
73- The `hash_serialized_2` value has been removed from `gettxoutsetinfo` since the value it
74  calculated contained a bug and did not take all data into account. It is superseded by
75  `hash_serialized_3` which provides the same functionality but serves the correctly calculated hash. (#28685)
76
77- New fields `transport_protocol_type` and `session_id` were added to the `getpeerinfo` RPC to indicate
78  whether the v2 transport protocol is in use, and if so, what the session id is.
79
80- A new argument `v2transport` was added to the `addnode` RPC to indicate whether a v2 transaction connection
81  is to be attempted with the peer.
82
83- [Miniscript](https://bitcoin.sipa.be/miniscript/) expressions can now be used in Taproot descriptors for all RPCs working with descriptors. (#27255)
84
85- `finalizepsbt` is now able to finalize a PSBT with inputs spending [Miniscript](https://bitcoin.sipa.be/miniscript/)-compatible Taproot leaves. (#27255)
86
87Changes to wallet related RPCs can be found in the Wallet section below.
88
89New RPCs
90--------
91
92- `loadtxoutset` has been added, which allows loading a UTXO snapshot of the format
93  generated by `dumptxoutset`. Once this snapshot is loaded, its contents will be
94  deserialized into a second chainstate data structure, which is then used to sync to
95  the network's tip.
96
97  Meanwhile, the original chainstate will complete the initial block download process in
98  the background, eventually validating up to the block that the snapshot is based upon.
99
100  The result is a usable bitcoind instance that is current with the network tip in a
101  matter of minutes rather than hours. UTXO snapshot are typically obtained via
102  third-party sources (HTTP, torrent, etc.) which is reasonable since their contents
103  are always checked by hash.
104
105  You can find more information on this process in the `assumeutxo` design
106  document (<https://github.com/bitcoin/bitcoin/blob/master/doc/design/assumeutxo.md>).
107
108  `getchainstates` has been added to aid in monitoring the assumeutxo sync process.
109
110- A new `getprioritisedtransactions` RPC has been added. It returns a map of all fee deltas created by the
111  user with prioritisetransaction, indexed by txid. The map also indicates whether each transaction is
112  present in the mempool. (#27501)
113
114- A new RPC, `submitpackage`, has been added. It can be used to submit a list of raw hex
115transactions to the mempool to be evaluated as a package using consensus and mempool policy rules.
116These policies include package CPFP, allowing a child with high fees to bump a parent below the
117mempool minimum feerate (but not minimum relay feerate). (#27609)
118
119  - Warning: successful submission does not mean the transactions will propagate throughout the
120    network, as package relay is not supported.
121
122  - Not all features are available. The package is limited to a child with all of its
123    unconfirmed parents, and no parent may spend the output of another parent.  Also, package
124    RBF is not supported. Refer to doc/policy/packages.md for more details on package policies
125    and limitations.
126
127  - This RPC is experimental. Its interface may change.
128
129- A new RPC `getaddrmaninfo` has been added to view the distribution of addresses in the new and tried table of the
130  node's address manager across different networks(ipv4, ipv6, onion, i2p, cjdns). The RPC returns count of addresses
131  in new and tried table as well as their sum for all networks. (#27511)
132
133- A new `importmempool` RPC has been added. It loads a valid `mempool.dat` file and attempts to
134  add its contents to the mempool. This can be useful to import mempool data from another node
135  without having to modify the datadir contents and without having to restart the node. (#27460)
136    - Warning: Importing untrusted files is dangerous, especially if metadata from the file is taken over.
137    - If you want to apply fee deltas, it is recommended to use the `getprioritisedtransactions` and
138      `prioritisetransaction` RPCs instead of the `apply_fee_delta_priority` option to avoid
139      double-prioritising any already-prioritised transactions in the mempool.
140
141Updated settings
142----------------
143
144- `bitcoind` and `bitcoin-qt` will now raise an error on startup
145 if a datadir that is being used contains a bitcoin.conf file that
146 will be ignored, which can happen when a datadir= line is used in
147 a bitcoin.conf file. The error message is just a diagnostic intended
148 to prevent accidental misconfiguration, and it can be disabled to
149 restore the previous behavior of using the datadir while ignoring
150 the bitcoin.conf contained in it. (#27302)
151
152- Passing an invalid `-debug`, `-debugexclude`, or `-loglevel` logging configuration
153  option now raises an error, rather than logging an easily missed warning. (#27632)
154
155Changes to GUI or wallet related settings can be found in the GUI or Wallet section below.
156
157New settings
158------------
159
160Tools and Utilities
161-------------------
162
163- A new `bitcoinconsensus_verify_script_with_spent_outputs` function is available in libconsensus which optionally accepts the spent outputs of the transaction being verified.
164- A new `bitcoinconsensus_SCRIPT_FLAGS_VERIFY_TAPROOT` flag is available in libconsensus that will verify scripts with the Taproot spending rules.
165
166Wallet
167------
168
169- Wallet loading has changed in this release. Wallets with some corrupted records that could be
170  previously loaded (with warnings) may no longer load. For example, wallets with corrupted
171  address book entries may no longer load. If this happens, it is recommended
172  load the wallet in a previous version of Bitcoin Core and import the data into a new wallet.
173  Please also report an issue to help improve the software and make wallet loading more robust
174  in these cases. (#24914)
175
176- The `createwallet` RPC will no longer create legacy (BDB) wallets when
177  setting `descriptors=false` without also providing the
178  `-deprecatedrpc=create_bdb` option. This is because the legacy wallet is
179  being deprecated in a future release. (#28597)
180
181- The `gettransaction`, `listtransactions`, `listsinceblock` RPCs now return
182  the `abandoned` field for all transactions. Previously, the "abandoned" field
183  was only returned for sent transactions. (#25158)
184
185- The `listdescriptors`, `decodepsbt` and similar RPC methods now show `h` rather than apostrophe (`'`) to indicate
186  hardened derivation. This does not apply when using the `private` parameter, which
187  matches the marker used when descriptor was generated or imported. Newly created
188  wallets use `h`. This change makes it easier to handle descriptor strings manually.
189  E.g. the `importdescriptors` RPC call is easiest to use `h` as the marker: `'["desc": ".../0h/..."]'`.
190  With this change `listdescriptors` will use `h`, so you can copy-paste the result,
191  without having to add escape characters or switch `'` to 'h' manually.
192  Note that this changes the descriptor checksum.
193  For legacy wallets the `hdkeypath` field in `getaddressinfo` is unchanged,
194  nor is the serialization format of wallet dumps. (#26076)
195
196- The `getbalances` RPC now returns a `lastprocessedblock` JSON object which contains the wallet's last processed block
197  hash and height at the time the balances were calculated. This result shouldn't be cached because importing new keys could invalidate it. (#26094)
198
199- The `gettransaction` RPC now returns a `lastprocessedblock` JSON object which contains the wallet's last processed block
200  hash and height at the time the transaction information was generated. (#26094)
201
202- The `getwalletinfo` RPC now returns a `lastprocessedblock` JSON object which contains the wallet's last processed block
203  hash and height at the time the wallet information was generated. (#26094)
204
205- 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)
206
207- For RPC methods which accept `options` parameters ((`importmulti`, `listunspent`,
208  `fundrawtransaction`, `bumpfee`, `send`, `sendall`, `walletcreatefundedpsbt`,
209  `simulaterawtransaction`), it is now possible to pass the options as named
210  parameters without the need for a nested object. (#26485)
211
212This means it is possible make calls like:
213
214```sh
215src/bitcoin-cli -named bumpfee txid fee_rate=100
216```
217
218instead of
219
220```sh
221src/bitcoin-cli -named bumpfee txid options='{"fee_rate": 100}'
222```
223
224- The `deprecatedrpc=walletwarningfield` configuration option has been removed.
225  The `createwallet`, `loadwallet`, `restorewallet` and `unloadwallet` RPCs no
226  longer return the "warning" string field. The same information is provided
227  through the "warnings" field added in v25.0, which returns a JSON array of
228  strings. The "warning" string field was deprecated also in v25.0. (#27757)
229
230- The `signrawtransactionwithkey`, `signrawtransactionwithwallet`,
231  `walletprocesspsbt` and `descriptorprocesspsbt` calls now return the more
232  specific RPC_INVALID_PARAMETER error instead of RPC_MISC_ERROR if their
233  sighashtype argument is malformed. (#28113)
234
235- RPC `walletprocesspsbt`, and `descriptorprocesspsbt` return
236  object now includes field `hex` (if the transaction
237  is complete) containing the serialized transaction
238  suitable for RPC `sendrawtransaction`. (#28414)
239
240- It's now possible to use [Miniscript](https://bitcoin.sipa.be/miniscript/) inside Taproot leaves for descriptor wallets. (#27255)
241
242Descriptors
243-----------
244
245- The usage of hybrid public keys in output descriptors has been removed. Hybrid
246  public keys are an exotic public key encoding not supported by output descriptors
247  (as specified in BIP380 and documented in doc/descriptors.md). Bitcoin Core would
248  previously incorrectly accept descriptors containing such hybrid keys. (#28587)
249
250GUI changes