Bitcoin Core wallets · 2025–2026

An Old wallet.dat Cannot Simply Be Opened in a New Release

Bitcoin Core 30.0 stopped directly loading legacy BDB wallets and provided a migration path. A rare migration failure then showed why an archival wallet file should never be tested without copies and the right software version.

Two wallet generations

Early Bitcoin Core wallets stored keys and metadata in Berkeley DB, or BDB. The project later moved to descriptor wallets, where key and address derivation is explicit and data is stored in SQLite.

Bitcoin Core 30.0 no longer creates or directly loads legacy BDB wallets. It provides a migration path to the modern format.

This does not make BTC disappear

A software update does not move bitcoin or erase it from the blockchain. The UTXOs remain on the network. The risk concerns the ability to read an old file correctly and recover the keys required to spend them.

“An obsolete wallet” therefore describes a file format and software support, not an expiration date for BTC.

A rare migration bug

On January 5, 2026, developers warned about a bug in Bitcoin Core 30.0 and 30.1. In a rare failed migration of an unnamed wallet.dat, the program could delete every file in the wallet directory, potentially causing loss of funds.

Binaries for the affected releases were removed from the official site, and users were asked not to perform wallet migrations through the GUI or RPC until a fix arrived. Other users of those versions were not considered affected.

The corrective release

Bitcoin Core 30.2 was released on January 10. It replaced the affected releases and restored a safer upgrade path.

The episode matters not because every old wallet was damaged—the bug required unusual circumstances—but because the consequence for a sole surviving copy could be irreversible.

A practical archival lesson

An old wallet.dat should first be preserved as a historical carrier of access: make several immutable copies, record their checksums, and work only with a duplicate.

Do not open the only file with the first new program available. The format, Bitcoin Core version, file condition, and migration procedure all matter. A wallet holds not coins, but the ability to prove authority over them.

A file may contain access, but recovering that access safely depends on its format, the software version, and backups.

Never experiment on the only copy of an old wallet.dat. Work from copies and do not send the file or keys to unknown services.

Unless stated otherwise, the text, conclusions, structure and editorial arrangement were created by the project editors. Facts, quotations and source materials remain attributable to their authors and rights holders.