kernel: Chainparams and headerssync updates pre-31.0 by achow101 · Pull Request #34677 · bitcoin/bitcoin

achow101 · 2026-02-26T00:33:30Z

Update chainparams and headerssync params per the release process.

Also added new assumeutxo snapshots for each network. I've uploaded snapshots to https://achow101.com/files/utxo-snapshots/

DrahtBot · 2026-02-26T00:34:10Z

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Reviews

See the guideline for information on the review process.

Type	Reviewers
ACK	janb84, Sjors, sipa, jaonoctus, fjahr

If your review is incorrectly listed, please copy-paste  into the comment that the bot should ignore.

Conflicts

Reviewers, this pull request conflicts with the following ones:

#26201 (Remove Taproot BIP 9 deployment by Sjors)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

LLM Linter (✨ experimental)

Possible places where named args for integral literals may be used (e.g. func(x, /*named_arg=*/0) in C++, and func(x, named_arg=0) in Python):

[datetime(2028, 10, 10)] in contrib/devtools/headerssync-params.py

^{2026-02-26 07:23:28}

janb84

ACK 44538f8

Checked some hashes with block heights /chainwork / getchaintxstats, all match (for mainnet. testnets checked only public information)

Mainnet:
https://mempool.space/block/00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac => 938'343

MinimumChainwork matches:

Details

bitcoin-cli getblockheader 00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac
{
  "hash": "00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac",
  "height": 938343,
[...]
  **"chainwork": "0000000000000000000000000000000000000001128750f82f4c366153a3a030"**,
}

https://mempool.space/block/0000000000000000000147034958af1652b2b91bba607beacc5e72a56f0fb5ee = > 935'000

getchaintxstats match ;

Details

bitcoin-cli getchaintxstats 4096 00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac
{
  "time": 1772055173,
  "txcount": 1315805869,
  "window_final_block_hash": "00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac",
  "window_final_block_height": 938343,
  "window_block_count": 4096,
  "window_interval": 2346169,
  "window_tx_count": 12671917,
  "txrate": 5.40111006496122
}

Testnet 3

https://mempool.space/testnet/block/000000007a61e4230b28ac5cb6b5e5a0130de37ac1faf2f8987d2fa6505b67f4 => 4'842'348

https://mempool.space/testnet/block/00000000000000f4971a7fb37fbdff89315b69a2e1920c467654a382f0d64786 => 4'840'000

Testnet 4

https://mempool.space/testnet4/block/0000000002368b1e4ee27e2e85676ae6f9f9e69579b29093e9a82c170bf7cf8a => 123'613

https://mempool.space/testnet4/block/000000000bd2317e51b3c5794981c35ba894ce27d3e772d5c39ecd9cbce01dc8 => 120'000

Signet

https://mempool.space/signet/block/00000008414aab61092ef93f1aacc54cf9e9f16af29ddad493b908a01ff5c329 => 293'175

https://mempool.space/signet/block/0000000577f2741bb30cd9d39d6d71b023afbeb9764f6260786a97969d5c9ac0 => 290'000

jaonoctus

I've validated the new chainparams and headerssync against my own nodes. I'll be hosting the new torrent snapshot files at https://bitcoin-snapshots.jaonoctus.dev once this PR is merged.

mainnet

m_assumeutxo_data @ 935'000
chainTxData @ 935'000
consensus.nMinimumChainWork @ 938'343
consensus.defaultAssumeValid @ 938'343

magnet:?xt=urn:btih:3492d082655d173d3459f7a5e454f3dd4ed0101b&dn=utxo-935000.dat&tr=udp%3A%2F%2Ftracker.bitcoin.sprovoost.nl%3A6969&tr=udp%3A%2F%2Ftracker.opentrackr.org%3A1337%2Fannounce

sha256: e572ddbe456d254f05fb004cebe225bdb3656074b66f0e9b1c7fa83e1301d486

Details

$ sha256sum utxo-935000.dat
e572ddbe456d254f05fb004cebe225bdb3656074b66f0e9b1c7fa83e1301d486

$ bitcoin-cli getblockhash 935000
0000000000000000000147034958af1652b2b91bba607beacc5e72a56f0fb5ee

$ bitcoin-cli getblockhash 938343
00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac

# tip: 935'000
$ bitcoin-cli gettxoutsetinfo hash_serialized_3
{
  "height": 935000,
  "bestblock": "0000000000000000000147034958af1652b2b91bba607beacc5e72a56f0fb5ee",
  "txouts": 164241311,
  "bogosize": 12870854130,
  "hash_serialized_3": "e4b90ef9eae834f56c4b64d2d50143cee10ad87994c614d7d04125e2a6025050",
  "total_amount": 19984148.03206779,
  "transactions": 113879165,
  "disk_size": 13290295029
}

# tip: 935'000
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1770215102,
  "txcount": 1305397408,
  "window_final_block_hash": "0000000000000000000147034958af1652b2b91bba607beacc5e72a56f0fb5ee",
  "window_final_block_height": 935000,
  "window_block_count": 4096,
  "window_interval": 2660438,
  "window_tx_count": 11723636,
  "txrate": 4.406656347563822
}

# tip: 938'343
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1772055173,
  "txcount": 1315805869,
  "window_final_block_hash": "00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac",
  "window_final_block_height": 938343,
  "window_block_count": 4096,
  "window_interval": 2346169,
  "window_tx_count": 12671917,
  "txrate": 5.40111006496122
}

$ bitcoin-cli getblockheader 00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac
{
  "hash": "00000000000000000000ccebd6d74d9194d8dcdc1d177c478e094bfad51ba5ac",
  "confirmations": 1,
  "height": 938343,
  "version": 671891456,
  "versionHex": "280c4000",
  "merkleroot": "1bd0deca15c01a0b62b9f56b5310004d41678c8be829b2ec5fc93ff3a8041c00",
  "time": 1772055173,
  "mediantime": 1772052403,
  "nonce": 3140788553,
  "bits": "1701f303",
  "target": "00000000000000000001f3030000000000000000000000000000000000000000",
  "difficulty": 144398401518100.9,
  "chainwork": "0000000000000000000000000000000000000001128750f82f4c366153a3a030",
  "nTx": 3963,
  "previousblockhash": "00000000000000000000bf88bc08552c46937df889b9e0cfe1141da456923b3c"
}

testnet4

m_assumeutxo_data @ 120'000
chainTxData @ 120'000
consensus.nMinimumChainWork @ 123'613
consensus.defaultAssumeValid @ 123'613

magnet:?xt=urn:btih:25733a7e451ca435f2901921b805c167f560424d&dn=utxo-testnet4-120000.dat&tr=udp%3A%2F%2Ftracker.bitcoin.sprovoost.nl%3A6969&tr=udp%3A%2F%2Ftracker.opentrackr.org%3A1337%2Fannounce

sha256: 093b44c537d207d7daf3367b00e7c71323d0163b7ae3d73f76ea05479a945f9c

Details

$ bitcoin-cli getblockhash 120000
000000000bd2317e51b3c5794981c35ba894ce27d3e772d5c39ecd9cbce01dc8

$ bitcoin-cli getblockhash 123613
0000000002368b1e4ee27e2e85676ae6f9f9e69579b29093e9a82c170bf7cf8a

# tip: 120'000
$ bitcoin-cli gettxoutsetinfo hash_serialized_3
{
  "height": 120000,
  "bestblock": "000000000bd2317e51b3c5794981c35ba894ce27d3e772d5c39ecd9cbce01dc8",
  "txouts": 13870119,
  "bogosize": 1142705000,
  "hash_serialized_3": "10b05d05ad468d0971162e1b222a4aa66caca89da2bb2a93f8f37fb29c4794b0",
  "total_amount": 5999799.97251533,
  "transactions": 9181935,
  "disk_size": 1023009172
}

# tip: 120'000
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1769234583,
  "txcount": 14141057,
  "window_final_block_hash": "000000000bd2317e51b3c5794981c35ba894ce27d3e772d5c39ecd9cbce01dc8",
  "window_final_block_height": 120000,
  "window_block_count": 4096,
  "window_interval": 2168096,
  "window_tx_count": 56313,
  "txrate": 0.02597348087907547
}

# tip: 123'613
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1772013387,
  "txcount": 14191421,
  "window_final_block_hash": "0000000002368b1e4ee27e2e85676ae6f9f9e69579b29093e9a82c170bf7cf8a",
  "window_final_block_height": 123613,
  "window_block_count": 4096,
  "window_interval": 2993163,
  "window_tx_count": 55331,
  "txrate": 0.01848579579528412
}

$ bitcoin-cli getblockheader 0000000002368b1e4ee27e2e85676ae6f9f9e69579b29093e9a82c170bf7cf8a
{
  "hash": "0000000002368b1e4ee27e2e85676ae6f9f9e69579b29093e9a82c170bf7cf8a",
  "confirmations": 9,
  "height": 123613,
  "version": 1073733632,
  "versionHex": "3fffe000",
  "merkleroot": "0e9f83f33fc7913d7c088411675c5fc8f22fc9f796d6afde7a1b1938da4242e6",
  "time": 1772013387,
  "mediantime": 1772007382,
  "nonce": 2783855826,
  "bits": "1d00ffff",
  "target": "00000000ffff0000000000000000000000000000000000000000000000000000",
  "difficulty": 1,
  "chainwork": "0000000000000000000000000000000000000000000009a0fe15d0177d086304",
  "nTx": 1,
  "previousblockhash": "0000000009feb85d0c1076552f914835055a86032fdbcce1c821b5a624acfa00",
  "nextblockhash": "0000000007f977533c5fa7d5de287be9d3b30f63dfbf4e17648f6e5d0a4e907c"
}

testnet3

m_assumeutxo_data @ 4'840'000
chainTxData @ 4'840'000
consensus.nMinimumChainWork @ 4'842'348
consensus.defaultAssumeValid @ 4'842'348

magnet:?xt=urn:btih:dfe62321ec8e9538a47e4f019d34a88510eaa751&dn=utxo-testnet-4840000.dat&tr=udp%3A%2F%2Ftracker.bitcoin.sprovoost.nl%3A6969&tr=udp%3A%2F%2Ftracker.opentrackr.org%3A1337%2Fannounce

sha256: eacaf9f1cdf6ddcc182ca255ffa3c423b592aede0abdbb4504079df586a22981

Details

$ bitcoin-cli getblockhash 4840000
00000000000000f4971a7fb37fbdff89315b69a2e1920c467654a382f0d64786

$ bitcoin-cli getblockhash 4842348
000000007a61e4230b28ac5cb6b5e5a0130de37ac1faf2f8987d2fa6505b67f4

# tip: 4'840'000
$ bitcoin-cli gettxoutsetinfo hash_serialized_3
{
  "height": 4840000,
  "bestblock": "00000000000000f4971a7fb37fbdff89315b69a2e1920c467654a382f0d64786",
  "txouts": 235037810,
  "bogosize": 18882533444,
  "hash_serialized_3": "ce6bb677bb2ee9789c4a1c9d73e6683c53fc20e8fdbedbdaaf468982a0c8db2a",
  "total_amount": 20999097.89823624,
  "transactions": 151886949,
  "disk_size": 16634570050
}

# tip: 4'840'000
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1770358647,
  "txcount": 536078574,
  "window_final_block_hash": "00000000000000f4971a7fb37fbdff89315b69a2e1920c467654a382f0d64786",
  "window_final_block_height": 4840000,
  "window_block_count": 4096,
  "window_interval": 1276608,
  "window_tx_count": 62368,
  "txrate": 0.04885446433047576
}

# tip: 4'842'348
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1772051651,
  "txcount": 536108416,
  "window_final_block_hash": "000000007a61e4230b28ac5cb6b5e5a0130de37ac1faf2f8987d2fa6505b67f4",
  "window_final_block_height": 4842348,
  "window_block_count": 4096,
  "window_interval": 2328088,
  "window_tx_count": 62660,
  "txrate": 0.02691479016257117
}

$ bitcoin-cli getblockheader 000000007a61e4230b28ac5cb6b5e5a0130de37ac1faf2f8987d2fa6505b67f4
{
  "hash": "000000007a61e4230b28ac5cb6b5e5a0130de37ac1faf2f8987d2fa6505b67f4",
  "confirmations": 1,
  "height": 4842348,
  "version": 536870912,
  "versionHex": "20000000",
  "merkleroot": "6c3083cb05ca4798dd4fb9343cf544a20e8172035b8645ad946195c4e0e91a68",
  "time": 1772051651,
  "mediantime": 1772045594,
  "nonce": 1509827168,
  "bits": "1d00ffff",
  "target": "00000000ffff0000000000000000000000000000000000000000000000000000",
  "difficulty": 1,
  "chainwork": "0000000000000000000000000000000000000000000017dde1c649f3708d14b6",
  "nTx": 17,
  "previousblockhash": "0000000032167e59d45f0861dc426ec95b6d5850e69121bde56ae6eb25eebd8a"
}

signet

m_assumeutxo_data @ 290'000
chainTxData @ 290'000
consensus.nMinimumChainWork @ 293'175
consensus.defaultAssumeValid @ 29'3175

magnet:?xt=urn:btih:304c3ee0ac2ce34ba64173b50d1950976544e8a3&dn=utxo-signet-290000.dat&tr=udp%3A%2F%2Ftracker.bitcoin.sprovoost.nl%3A6969&tr=udp%3A%2F%2Ftracker.opentrackr.org%3A1337%2Fannounce

sha256: 12d1b3f1e3488ddea251b8222e4ecf8552de2aa73c9fe05f94a08a1eb5eba367

Details

$ bitcoin-cli getblockhash 290000
0000000577f2741bb30cd9d39d6d71b023afbeb9764f6260786a97969d5c9ac0

$ bitcoin-cli getblockhash 293175
00000008414aab61092ef93f1aacc54cf9e9f16af29ddad493b908a01ff5c329

# tip: 290'000
$ bitcoin-cli gettxoutsetinfo hash_serialized_3
{
  "height": 290000,
  "bestblock": "0000000577f2741bb30cd9d39d6d71b023afbeb9764f6260786a97969d5c9ac0",
  "txouts": 59319793,
  "bogosize": 4753561406,
  "hash_serialized_3": "97267e000b4b876800167e71b9123f1529d13b14308abec2888bbd2160d14545",
  "total_amount": 12499727.17741007,
  "transactions": 11145919,
  "disk_size": 3498668523
}

# tip: 290'000
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1770163902,
  "txcount": 28547497,
  "window_final_block_hash": "0000000577f2741bb30cd9d39d6d71b023afbeb9764f6260786a97969d5c9ac0",
  "window_final_block_height": 290000,
  "window_block_count": 4096,
  "window_interval": 2459211,
  "window_tx_count": 158216,
  "txrate": 0.06433608177582159
}

# tip: 293'175
$ bitcoin-cli getchaintxstats 4096
{
  "time": 1772055248,
  "txcount": 28676833,
  "window_final_block_hash": "00000008414aab61092ef93f1aacc54cf9e9f16af29ddad493b908a01ff5c329",
  "window_final_block_height": 293175,
  "window_block_count": 4096,
  "window_interval": 2435790,
  "window_tx_count": 164090,
  "txrate": 0.06736623436338929
}

$ bitcoin-cli getblockheader 0000000002368b1e4ee27e2e85676ae6f9f9e69579b29093e9a82c170bf7cf8a
{
  "hash": "00000008414aab61092ef93f1aacc54cf9e9f16af29ddad493b908a01ff5c329",
  "confirmations": 1,
  "height": 293175,
  "version": 536870912,
  "versionHex": "20000000",
  "merkleroot": "664431bfbd5f0d84be6a71b5f19f936d6ecb6e3cfbbe315212b6eedc927408c6",
  "time": 1772055248,
  "mediantime": 1772050304,
  "nonce": 36906233,
  "bits": "1d150eea",
  "target": "000000150eea0000000000000000000000000000000000000000000000000000",
  "difficulty": 0.0474865840527392,
  "chainwork": "00000000000000000000000000000000000000000000000000000b463ea0a4b8",
  "nTx": 109,
  "previousblockhash": "0000000e14aa494dc78672c43bf4095b3360a597ded2fcb985ccd67aa76b0d7e"
}

Sjors · 2026-03-03T17:58:41Z

ACK 44538f8

signed

sipa

ACK 44538f8. I re-did all the mainnet parameters, but did not look closely at the other networks.

jaonoctus

ACK 44538f8

#34677 (review)

fjahr · 2026-03-06T23:53:36Z

ACK 44538f8

I have re-done the mainnet, testnet4 and signet params.

achow101 added 4 commits February 25, 2026 14:49

kernel: update assumed blockchain and chainstate sizes

5ca0c55

kernel: update defaultAssumeValid and minimumChainWork

8eaf1d2

kernel: update chainTxData

cf261b0

kernel: Update headerssync params

58c2e23

DrahtBot added the Validation label Feb 26, 2026

achow101 changed the title ~~kernel: Chainparams and headerssync updates~~ kernel: Chainparams and headerssync updates pre-31.0 Feb 26, 2026

achow101 added this to the 31.0 milestone Feb 26, 2026

kernel: Add recent assumeutxo snapshot info

44538f8

janb84 reviewed Feb 26, 2026

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DrahtBot mentioned this pull request Feb 27, 2026

Remove Taproot BIP 9 deployment #26201

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jaonoctus reviewed Feb 27, 2026

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DrahtBot requested a review from jaonoctus March 3, 2026 17:58

sipa reviewed Mar 5, 2026

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jaonoctus reviewed Mar 5, 2026

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fanquake merged commit d198635 into bitcoin:master Mar 8, 2026
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Sjors mentioned this pull request Mar 20, 2026

Drop testnet3 #31974

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kernel: Chainparams and headerssync updates pre-31.0#34677

kernel: Chainparams and headerssync updates pre-31.0#34677
fanquake merged 5 commits intobitcoin:masterfrom
achow101:31-chainparams

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mainnet

testnet4

testnet3

signet

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