Bitcoin Core Developer Warns Users to Pause BTC Transfers When BIP-110 Deadline Nears
Bitcoin Core developer Jon Atack is urging users to halt bitcoin transactions during the second week of August 2026, citing potential reorganization risk as the BIP-110 activation window approaches.
Atack posted a warning on X on June 29, 2026, stating he plans to run both a custom version of Bitcoin Core and Bitcoin Knots 110 side by side to monitor network behavior before the rules take effect. BIP-110 is a temporary soft fork proposal aimed at limiting arbitrary data in transactions, including large OP_RETURN outputs and inscriptions. New outputs would be capped at 34 bytes, with OP_RETURN allowed up to 83 bytes, and data pushes and witness elements capped at 256 bytes. UTXOs created before activation remain exempt, and the rule expires automatically after roughly a year.
Mandatory signaling begins around block 961,632, projected for early August 2026. As of July 2, signaling sits at about 0.76% in the current difficulty period, with the block height in the mid-956,000s. Knots-based nodes make up an estimated 8% to 22% of the network, but miner hashpower backing the change remains extremely thin, increasing the risk of short reorgs, slower blocks, or mempool divergence once the mandatory signaling period starts.
Luke Dashjr responded to Atack’s thread, arguing there is no reorg risk for users who have already upgraded to BIP-110. However, some community members pushed back, questioning the need to sideline funds, and one user called for actively testing the network by placing large OP_RETURN and inscriptions in every block for 144 blocks, a tactic proponents of those features are likely to employ.
Atack’s dual-node setup allows operators to track a possible chain split using standard RPC calls like getblockchaininfo and getchaintips, comparing block heights, mempool contents, and rejected-block log entries in real time. For holders, recommended steps include moving funds off exchanges into self-custody before the mandatory signaling period, deferring large transfers, and waiting for extra confirmations if transactions cannot be postponed. Exchanges may announce preliminary plans for a chain split possibility before the deadline.
If BIP-110 locks in, full data-limiting rules follow roughly 2,016 blocks after the mandatory signaling period ends, pushing activation into mid-to-late August or early September. The rule then runs for about a year before expiring. Atack characterized his position as neutral, presenting the approach as observation rather than a forecast. While a chain split remains a possibility, it is not widely expected. Unlike the intentional August eCash fork, which will produce two separate chains and two coins, BIP-110’s outcome depends on signaling data over the coming weeks.