Bitcoin Core developers warned of a wallet migration bug in versions 30.0 and 30.1, potentially leading to fund loss. The bug affects migrations from old wallets not renamed or upgraded, triggered when migrating an unnamed legacy wallet file, resulting in deletion of the entire wallet directory without external backup.

Bitcoin Core released a fix with version 30.1 after pulling the faulty binaries from the official site. Users are advised not to use migration tools until the fixed release of Bitcoin Core 30.2. Proficient users can assess their risk by checking version, wallet type, pruning status, migration attempts, and directory layout.

Bitcoin Core dominates Bitcoin nodes with 78% using it, emphasizing the impact of a wallet bug in the wider ecosystem. Concentration risk is a concern, as bugs in the dominant implementation can have significant repercussions. Though not consensus-critical, the bug highlights how wallet issues in a dominant implementation can escalate into ecosystem-wide problems.

Read more at Cointelegraph: Bitcoin Core v30 Bug Can Delete Files When Migrating Legacy Wallets