A Bitcoin Core v30 bug has been recently disclosed by Bitcoin Core Developers, stating that, under rare conditions, this issue has the potential to destroy all files within a user’s wallet folder due to unsuccessful migration. Users could potentially lose their funds permanently.
A Dangerous Flaw in Wallet Upgrade Logic
The Bitcoin Core development team has issued an urgent warning about a dangerous Bitcoin Core v30 bug present in the most recent released versions 30.0 and 30.1. The bug appeared in the wallet migration process, the phase that is designed to upgrade old, legacy wallet.dat files to an updated format.
The team says that “under specific circumstances,” primarily when migrating an unnamed legacy wallet file located in a custom directory with pruning enabled, if the migration goes wrong, the cleanup logic flow can erroneously delete the entire wallet directory instead of just the temporary files.
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Narrow Scope, High Stakes
While the Bitcoin Core v30 bug only affects a small group of users, for instance, those with very old wallet configurations who actively attempt a migration, the consequences could be severe. If the bug triggers and the user lacks a current external backup (which is recommended), loss of access to funds is “effectively guaranteed” as all local wallet files are removed.
In light of this, the developers have removed the download option for the affected versions of Bitcoin Core from their online website until they can provide users with all the latest software fixes. They have also warned all users not to try to migrate their wallets using the Graphical User Interface (GUI) or Remote Procedure Call (RPC) interface until the fixed version 30.2 is released.
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A Reminder of Ecosystem Concentration Risk
This Bitcoin Core v30 bug underscores a wider systemic risk within the Bitcoin network: the overwhelming dominance of a single node implementation.
So far, with Bitcoin Core running approximately 78% of reachable nodes, and therefore any type of bugs within the structure (such as a bug relating to the wallet management layer) have the potential to create an impact with outsized consequences for the ecosystem.
For this reason, no matter what software users are currently using to host their Bitcoin wallets, it is important to take preventive steps to ensure complete and updated copies of the Bitcoin wallet files are maintained safely.
FAQs
I’m running Bitcoin Core 30.0/30.1 but not migrating a wallet. Am I safe?
Yes. The developers confirm that if you are not actively attempting to migrate a legacy wallet, your existing installation is unaffected. You can continue running your node and using existing wallets normally.
How do I know if I’m at risk or affected by the Bitcoin Core v30 bug?
You are at risk if you:
1) You are running v30.0 or 30.1
2) Have a very old, unnamed wallet.dat file (not created by default since 2019),
3) Have pruning enabled
4) Attempt to migrate that wallet.
If you have not yet attempted a migration, create a full backup of your data directory immediately and wait for v30.2.
What should I do now?
If you are on v30.0 or 30.1, do not use the wallet migration feature. Make sure you have a secure backup of your wallet.dat file(s). Wait for the official release of Bitcoin Core version 30.2 containing the fix before attempting any upgrade or migration plan.
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