Bitcoin Core Will Not Open an Old Wallet: Version Compatibility or Corruption?

First steps: the exact error matters more than a paraphrase

1. Record the Bitcoin Core version, operating system and action that triggered the error.
2. Establish whether you selected an existing wallet, backup restoration or migration.
3. Save the full message separately, removing personal paths and names from any public version.
4. Check that the file exists at the selected path and whether other instances of the application are running.
5. Preserve the original; modify only a separate copy after choosing the appropriate procedure.

Do not create a new wallet over the old directory just to make the error disappear. An empty new wallet does not restore the old keys. The wallet.dat guide covers inventory and copy preservation.

Three diagnostic branches based on the messages

These situations are covered by the Bitcoin Core project's functional tests; the sources link to the version 30.2 test file. This is an explanation of documented scenarios, not a claim that the editorial team ran a client's wallet. Exact wording and conditions may differ in another version.

Educational example: a user selected an empty folder named after the old wallet instead of the backup itself. A format-recognition error in that situation says nothing about the condition of a file that was never opened. First compare the selected path with the inventory, then use the standard restoration procedure for the appropriate file.

If the database is in use, first determine which application is using it and close that application properly. Do not delete service files or terminate processes blindly: they may be serving an active wallet.

Old legacy wallets and migration

Starting with Bitcoin Core 30.0, old BDB wallets cannot simply be loaded in the usual way. Migration is provided for the transition to the descriptor format. Instructions for older versions involving replacement of wallet.dat or removed RPC commands may therefore be unsuitable.

The exact migration version also matters: a warning was published for 30.0 and 30.1 about possible file deletion after a failed migration under certain conditions. These versions should not be used for migration; fixes were released in 30.2. Check the documentation for the selected supported version and keep an independent copy of everything needed before making changes.

The plan should specify the original copy, destination directory, version and success criteria: the required addresses, availability of keys or an external signing device, and history verification. If a step is unclear, stop before writing changes rather than after several different attempts.

When to suspect corruption and what to tell a specialist

Disk read errors, different sizes in repeated copies, sudden storage-device disconnections and a truncated file call for a data-integrity check. They do not prove that everything is lost, but they change the order of work: preserve the storage device first, then experiment with the wallet. Ordinary password searching does not repair a corrupted database.

For a recovery assessment, useful details include the version, exact error, copy size and origin, storage-device condition and actions already taken. Do not attach the file or secrets to the initial inquiry. A specialist needs to determine which stage is failing: finding the path, reading the format, migration or decryption.

If the wallet already loads and only the balance is wrong, that is the next task: checking after recovery. If you are unsure which application originally held the wallet, use the Bitcoin wallet overview.