Bitcoin Core developers issued an urgent notice after discovering a wallet migration bug in versions 30.0 and 30.1 that can, in rare cases, delete wallet files on the same node, turning a routine upgrade step into a potential funds-loss event for users without backups.
In a Jan. 5 statement, the Bitcoin Core Project warned on X that “under rare circumstances, migrating a legacy (BDB) wallet can delete all wallet files on the same node. If those wallets aren’t backed up, this can result in a loss of funds.”
The team said a fix is slated for Bitcoin Core 30.2 and advised users not to migrate legacy wallets using 30.0 or 30.1 until that release is available. “Only the legacy wallet migration process is affected. All other uses are unaffected. You can continue using Bitcoin Core normally, including existing wallets and running a node without wallets.”
Bitcoin Community Divided Over Severity
The disclosure caps a simmering thread of reports and frustration among users tracking the issue on GitHub. One X user, posting under the handle @B__T__C, claimed “several users had been reporting it for over two weeks” and argued the bug proved difficult for maintainers to reproduce, linking to a public issue thread.
Another account, Greg Tonoski (@GregTonoski), pointed to earlier warnings ahead of the v30 release and suggested the episode reflects a broader disconnect between developers and users. “Users had warned @bitcoincoreorg (@achow101) a month before the v30 release,” he wrote, adding: “I am starting to doubt if Bitcoin is still catering to the Bitcoin user’s needs.”
The sharpest debate, however, has been over how “rare” translates into real-world risk, especially given the migration path that v30 users may face. @barackomaba argued the impact is being understated because Bitcoin Core v30.0 “explicitly stopped loading or creating BDB legacy wallets,” leaving affected users with a practical next step: migrate.
“People are acting like legacy wallet migration is some obscure edge case,” the account wrote. “But v30.0 explicitly stopped loading or creating BDB legacy wallets, so anyone who upgraded to v30 and still had a legacy wallet in Bitcoin Core effectively had only one path forward: migrate.”
‘Legacy wallets’ were the default wallet type until April 2022 (before 23.0, new wallets were ‘legacy’ by default). Also, the migration needs to fail. This won’t be the majority of migrations obviously, but there are many plausible ways to trigger this.”
He then described one such scenario: a user pruning their node while the wallet wasn’t loaded, which can cause the migrated wallet load step to fail, sending the process down a “cleanup path” that deletes the entire wallet directory and “everything in it,” including other wallets and even rollback backups created during migration.
Not everyone agreed the incident merits alarm. @w_s_bitcoin pushed back by emphasizing adoption and observed impact, arguing that Core v30 “currently” accounts for “1/5th of all the Bitcoin nodes” and that “reportedly only one single user was affected by this bug.” Wicked characterized it as “a shitty bug,” but added that it “didn’t result in any known bitcoin losses,” and said the fix is welcome.
What is not in dispute, based on Bitcoin Core’s own notice, is the practical guidance: users running 30.0 or 30.1 should avoid migrating legacy (BDB) wallets until 30.2 ships, and ensure wallet files are backed up before attempting any migration at all.
At press time, Bitcoin traded at $91,717.
