The Bitcoin Core team warned on January 5th of a critical error in the wallet migration process that exists in versions 30.0 and 30.1 of the software.
According to the description, “under rare circumstances” an attempt to convert a legacy wallet (an old wallet stored in Berkeley DB format) could result in the deletion of all wallet files hosted on the same node if it fails.
If you don’t have a backup copy, There is a direct risk of loss of funds. The development team recommended not performing the migration process until a new fixed version of Bitcoin Core (in this case, corresponding to 30.2) is published.
The incident will take place one year later intense discussion in the bitcoiner community For Bitcoin Core v30, among other changes, it was a version that expanded on the use of the OP_RETURN opcode to embed arbitrary data in transactions, a decision that sparked controversy in 2025.
Bitcoin Core v30 bug only affects migration of old wallets
Legacy wallet migration is a mechanism to convert older wallets to the newer format used by Bitcoin Core.
he bug It does not affect the general functionality of the node or the day-to-day use of existing wallets. Only affects migration of legacy wallets using v30.0 or v30.1..
Bitcoin Core has made it clear that all other usages remain the same. This means you can continue running your node, use your existing wallet, and operate normally. This fix will be delivered in Bitcoin Core 30.2. Until then, we recommend not migrating legacy wallets to 30.0/30.1.
As an additional measure, the binary (installation executable) v30.0 and v30.1 have been labeled “unsecure”. On the official website, the recommended download was once again Bitcoin Core 28.1. This is an earlier version that is considered stable and does not include the removal of the OP_RETURN restriction.
Reactions and criticism from the community
Bitcoiner developer Tomer Strolight called this issue harshly:
This is pretty serious if I’m reading you correctly. If you are trying to migrate a legacy wallet, Bitcoin Core 30.x may delete all wallets on your device. Of course, you should always maintain backups, but this is so serious that Core has removed v30.x from the recommended versions of their site.
Tomer Strolight, Bitcoin developer.
Strolight added that given the focus so far on installing v30 to improve security, there needs to be widespread and proactive communication about this. bug: “The person behind that installation should issue a widespread warning before someone loses all their wallet files.”
This episode highlights two important points. First, the importance of backups. Wallets without backups are always a risk.
Second, even audited and critical software can make errors with serious consequences. The team’s response (public warnings, binary removal, and planned patches) is aimed at containing the impact.
Until Bitcoin Core 30.2 is published, the guidance is clear: don’t migrate your v30 legacy wallets, keep backups, and choose 28.1 if you want a stable installation.