Bitcoin Cash upgrades
A protocol upgrade every May, on schedule. Here is each one, what it changed and why.
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May 15, 2027 · proposed
May 2027 upgrade (not yet decided)
Nothing is locked in yet. The main candidate is CHIP-2025-03 Faster Blocks (1-minute blocks). The lock-in decision falls around 15 November 2026; 2027 could also ship with no consensus changes.
Verified -
May 15, 2026 · activated · block 951,145
May 2026 (Layla): loops, functions, bitwise ops and Pay-to-Script
Four CHIPs: bounded loops (OP_BEGIN/OP_UNTIL), reusable functions (OP_DEFINE/OP_INVOKE), re-enabled bitwise and shift ops, and standard Pay-to-Script outputs with 128-byte NFT commitments.
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May 15, 2025 · activated · block 898,374
May 2025: VM Limits and BigInt
Replaced the 201-opcode and 520-byte limits with cost-based density limits, raised stack items to 10,000 bytes, and removed the number-size limit for high-precision math.
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May 15, 2024 · activated · block 845,891
May 2024: ABLA, the adaptive block size limit
The block size limit now adjusts itself every block, based on how full recent blocks were. 32 MB remains the floor.
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May 15, 2023 · activated · block 792,773
May 2023: CashTokens, P2SH32 and smaller transactions
Native fungible tokens and NFTs (CashTokens), 32-byte P2SH for stronger contract security, a 65-byte minimum transaction size, and transaction versions restricted to 1 and 2.
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May 15, 2022 · activated · block 740,238
May 2022: native introspection and 64-bit math
Contracts can read their own transaction directly (native introspection opcodes), do 64-bit arithmetic, and multiply with OP_MUL.
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May 15, 2021 · activated
May 2021: no chain limit, multiple OP_RETURNs
A relay-policy upgrade: the 50-transaction limit on chains of unconfirmed transactions was removed, and one transaction may carry several OP_RETURN outputs. No consensus rules changed.
Verified -
Nov 15, 2020 · activated · block 661,648
November 2020: ASERT difficulty adjustment (and the ABC split)
Replaced the 2017 DAA with ASERT (aserti3-2d), ending daily difficulty swings. Bitcoin ABC's rival ruleset, with an 8% coinbase levy, split off with almost no hashpower.
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May 15, 2020 · activated · block 635,259
May 2020: SigChecks and OP_REVERSEBYTES
Replaced SigOps counting with SigChecks, which counts signature checks actually executed, and added OP_REVERSEBYTES.
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Nov 15, 2019 · activated · block 609,136
November 2019: Schnorr multisig and MINIMALDATA
OP_CHECKMULTISIG gained Schnorr mode, and minimal push and minimal number encoding became consensus rules.
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May 15, 2019 · activated · block 582,680
May 2019: Schnorr signatures and SegWit recovery
OP_CHECKSIG and OP_CHECKDATASIG began accepting Schnorr signatures, and coins sent by mistake to SegWit P2SH addresses became recoverable.
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Nov 15, 2018 · activated · block 556,767
November 2018: CTOR, OP_CHECKDATASIG and the BSV split
Canonical transaction ordering (CTOR), OP_CHECKDATASIG, a 100-byte minimum transaction size, push-only and clean-stack rules. A rival group forked off as Bitcoin SV.
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May 15, 2018 · activated · block 530,356
May 2018: 32 MB blocks and restored opcodes
Raised the block size limit to 32 MB and re-enabled OP_CAT, OP_SPLIT, bitwise AND/OR/XOR, OP_DIV, OP_MOD, OP_NUM2BIN and OP_BIN2NUM.
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Nov 13, 2017 · activated · block 504,032
November 2017: new difficulty adjustment (DAA)
Replaced the emergency difficulty adjustment with a rolling ~144-block DAA, and made LOW_S and NULLFAIL signature rules consensus.
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Aug 1, 2017 · activated · block 478,559
August 2017: UAHF, the birth of Bitcoin Cash
The User Activated Hard Fork split Bitcoin Cash from Bitcoin: a bigger block size limit, mandatory replay protection (SIGHASH_FORKID) and an emergency difficulty adjustment.
Verified