Longtime Bitcoin developer Matt Corallo says there is an 80% chance that the “Great Consensus Cleanup,” first proposed in 2019, will be Bitcoin's next soft fork — a practical fix for issues that “everyone agrees are problems.”

The upgrade, formalized as BIP-54, targets four long-standing weaknesses in the network's consensus rules: poison blocks, time warp bugs, Merkle malleability and duplicate coinbase transactions. None is considered urgent, but all are real, according to Corallo, a co-author of the proposal.

Not everyone views a maintenance-focused soft fork as progress. Paul Sztorc, co-founder and CEO of LayerTwo Labs, has dismissed it as “depressing” janitorial work.

A cleanup years in the making

While debates over quantum resistance may command attention, many experts expect Bitcoin's next soft fork to be a practical cleanup — one spanning fixes for vulnerabilities in the network's difficulty adjustment mechanism as well as denial-of-service vectors among miners. Known as the Great Consensus Cleanup (BIP-54), the 2019 proposal seeks to address the “cruft” in Bitcoin's consensus design through changes that have historically been sidelined, according to Corallo.

A soft fork is a backward-compatible change to Bitcoin's consensus rules — the shared standards every full node uses to decide which blocks and transactions are valid — that tightens them in a way older software still accepts. Because flaws in these rules affect every node on the network at once, fixing them means coordinating an upgrade across the entire ecosystem rather than patching a single piece of software.

“There's a laundry list of things we know of that we really need to clean up,” he said during a recent appearance on MARA Foundation TV. “All of these issues are real concerns that could impact Bitcoin negatively, but they're not like, ‘Oh, the sky is falling.’”

Although no formal timeline has been set for the proposal, Corallo said during a conversation with Isabel Foxen Duke, head of the MARA Foundation, that there is an 80% chance the Great Consensus Cleanup comes next for the network. He also framed it as a practical exercise for Bitcoin developers who have not yet been through a soft fork.

Four vulnerabilities in scope

At its core, Corallo said, BIP-54 “fixes some stuff that everyone agrees are problems.” The proposal targets four specific vulnerabilities:

• Poison blocks: A miner seeking a temporary advantage over competitors could mine a specially crafted block that exploits performance bottlenecks, intentionally slowing down node validation for everyone else.
• Time warp bugs: A loophole in Bitcoin's two-week difficulty adjustment window allows miners controlling a majority of hashrate to manipulate block timestamps, artificially accelerating the rate at which new blocks are issued.
• Merkle malleability: Because a 64-byte transaction happens to be the exact same data size as an internal Merkle tree node, an attacker can theoretically forge proofs to trick light clients into accepting fake transactions.
• Duplicate coinbase transactions: Historical design quirks that allowed duplicate transaction IDs will resurface at future block heights, creating a vulnerability that could overwrite existing coins or disrupt ledger accounting.

“Kind of depressing”

Not everyone considers a maintenance-focused soft fork a win. Paul Sztorc, co-founder and CEO of LayerTwo Labs, called BIP-54's potential activation “kind of depressing, since it is a janitorial maintenance fork that doesn't do anything” in a post on X.

Surveying developers at TABconf in Atlanta, Sztorc noted that Bitcoin's “best and brightest” predominantly expect the Great Consensus Cleanup to be Bitcoin's next soft fork anyway, with the earliest estimate in September 2027 and most pointing to 2028 or later.

The politics of activation

Following the activation of Taproot in 2021, Bitcoin's community has faced years of gridlock surrounding protocol changes. This friction is frequently framed around “ossification,” with broader protocol changes like OP_CAT (BIP-347) and OP_CHECKTEMPLATEVERIFY (BIP-119) struggling to reach ecosystem-wide consensus.

Bitcoin has activated only a handful of soft forks in its history — Segregated Witness in 2017 and Taproot in 2021 among them — and each required broad coordination among developers, miners and node operators before the new rules took effect.

According to Corallo, soft forks have always involved overcoming technical hurdles, but more recently he has observed political and social friction that has become just as relevant. The Bitcoin community spent months debating how Taproot should be activated, with arguments pitting miner-signaling thresholds against mandatory user flag days.

Corallo argues that BIP-54 can establish a deployment playbook for future soft forks. “In every recent soft fork, there's also been a bunch of drama about activation mechanisms,” he said. “So hopefully we could do a soft fork to go through that drama, and then copy and paste and reuse it and head off some of that drama [for future soft forks].”

In that sense, BIP-54 is just as much about proving Bitcoin can still agree on upgrades at the social layer as it is about actual code cleanup.

This article was written by André Beganski, a Senior Content Manager at MARA Foundation who produces content on topics including the intersection of quantum computing and cryptography. He has previously worked for Decrypt.