Failure in the new version of Bitcoin could cause cryptocurrencies to disappear

Source: PortaldoBitcoin Original Title: Failures in new Bitcoin version could make cryptocurrencies disappear Original Link: https://portaldobitcoin.uol.com.br/falha-em-nova-versao-do-bitcoin-pode-fazer-criptomoedas-sumirem/ The Bitcoin Core developers issued an emergency alert after identifying a serious bug in versions 30.0 and 30.1 of the software, capable of deleting user wallets and causing the permanent loss of bitcoins in specific circumstances. The flaw led to the immediate removal of these versions from the project’s official website and reignited old tensions within the community, already sensitive due to the controversial protocol update related to the use of OP_RETURN.

According to the notice published by Bitcoin Core maintainers on Monday (5), the issue occurs during the migration process of old wallets, known as legacy wallets, which use the Berkeley DB format.

These wallets need to be converted to the modern format adopted by the client, but, in rare cases, a failure in this process can result in the deletion of all wallet files stored in the same directory as the node, not just the one being migrated. If the user does not have updated backups, the loss of funds is irreversible.

NOTICE: Wallet Migration bug present in Bitcoin Core wallet 30.0 & 30.1.

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.

A fix will become available in…

The developers explained that the bug requires an uncommon combination of factors, including the presence of a default wallet.dat file — which has not been created automatically since version 0.21, released about five years ago — and a failure to load this wallet. The problem can be triggered when the pruning feature, used to discard old blockchain data, is enabled and the wallet is closed during this process.

Still, as a precaution, the team decided to classify the binaries of versions 30.0 and 30.1 as “unsafe” and remove the download links.

While a definitive fix is being developed for version 30.2, the official recommendation is that users do not attempt to migrate legacy wallets in these versions, either through the graphical interface or via RPC.

However, the alert does not extend to everyday use of the software. Users already operating existing wallets can continue sending and receiving bitcoins, validating blocks and keeping their nodes running normally, as long as they do not initiate the process of converting old wallets.

As an additional measure, the official Bitcoin Core website has resumed recommending the download of version 28.1, considered stable and free from both the bug and the changes introduced in v30 related to OP_RETURN. This decision reinforced the perception of the episode’s severity, especially since version 30 was widely promoted throughout 2025 as a significant security update.

Community Reaction

Developer Tomer Strolight described the problem as “quite serious” and stated that, if his interpretation is correct, Bitcoin Core 30.x “could delete all wallets on the device.” For him, many users were encouraged to update the software precisely because of security alerts, making clear and preventive communication even more critical.

Strolight also noted that the fact that the developers themselves removed version 30.x from the recommended list highlights the magnitude of the error and requires a collective effort to warn users about the risk.

This is pretty bad if I’m reading it correctly. If you try to migrate one legacy wallet, bitcoin core 30.x can delete ALL wallets on the device. Of course you should always keep backups of all wallet files, but this is severe enough that, on its own site, core has removed v30.x…

The episode was quickly incorporated into the ideological debate that marked the launch of version 30. Some users took the incident as an opportunity to defend Luke Dash Jr.'s stance and the use of Bitcoin Knots, an alternative implementation of Bitcoin Core that imposes stricter restrictions on storing arbitrary data on the blockchain.

For these critics, the series of controversies reinforces the need for more conservative approaches in software development.