How to Fix “Unrecognized Database Format” in Microsoft Access
This error means Access can’t read the structure of your database file. Most of the time the file is corrupted. Sometimes it’s a version mismatch, where the file was created in a newer version of Access than the one opening it.
Common causes
- A network drop or power loss while someone was writing to the database
- Several users editing a database that isn’t split into a front-end and back-end
- Opening an .accdb file in Access 2003 or earlier, which only read .mdb files
- Newer features in the file (such as the Large Number data type) that older Access versions don’t support
How to fix it
- Make a copy of the file first. Work only on the copy.
- Check the Access version. If the file opens on another computer with a newer version of Access, the problem is the version, not corruption.
- Check for a stuck lock file. Look in the same folder for a file with the same name ending in .laccdb (or .ldb). If nobody is using the database, delete it.
- Run Compact and Repair on the copy. Open Access without a database, go to Database Tools, choose Compact and Repair Database, and select the copy.
- Import into a new database. If repair fails, create a blank database and use External Data > New Data Source > From Database > Access to import tables, queries, forms, and reports. Damaged objects often fail while the rest come through.
- Restore from backup if none of the above works.
Avoid making it worse
Don’t keep opening the corrupted original or running repair on it over and over. Each attempt can overwrite data that a professional could still recover.
Still not opening?
We can often recover data from corrupted Access databases, even files that won’t open at all. Book a free diagnostic or see our Access Database Repair service.