Member Avatar for John_162

Hi
I Have an App that connects to an 2010 access DB (.accdb) using OELDB Driver.
In my dev pc the application works fine.
I also tried installing it on different pc and it worked fine using a access database runtime.
Now when Installing it on a pc running access 365 I get ''Unrecognized Database format error'' even after installing the same access database runtime I still.
What could be causing this error?

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Short, practical diagnosis and fixes for “Unrecognized database format” when your app uses OLEDB against an .accdb (based on this thread). As noted, keeping Access/runtimes updated matters, and since confirmed the SP fixed his machine, also check a few compatibility items that commonly cause the same error on other PCs.

Common causes and quick checks

  • Mismatched bitness: a 32-bit app/process needs the 32‑bit ACE provider; a 64‑bit app needs the 64‑bit provider. Check Office/Access bitness in any Office app via File → Account → About. (support.microsoft.com)
  • Missing / wrong ACE engine: install the Microsoft Access Database Engine that matches your Office/Runtime bitness (or install the matching Access Runtime). The ACE redistributable installs the OLEDB/ODBC drivers your app uses. (microsoft.com)

Useful troubleshooting steps (do these in order)

  1. Try opening the .accdb directly with the Access runtime on the target PC. If Access itself fails, the problem is the engine/file, not your app.
  2. Confirm Office/Runtime bitness and the bitness your app runs as; change your app platform target or install the matching ACE/Runtime if they differ. (support.microsoft.com)
  3. If the provider is not registered, install the matching Access Database Engine (see Microsoft download details). After install, try a simple OLEDB connection like:
    Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Path\YourFile.accdb;Persist Security Info=False;

    (Use ACE.OLEDB.16.0 only if you have that engine installed.) (microsoft.com)

Other causes to rule out

  • Compiled frontend compatibility (an .accde built by a newer Access can fail on older runtimes) — recreate the ACCDE with the target runtime or update the runtime. (support.microsoft.com)
  • File corruption (compact/repair, restore backup). Microsoft documents “unrecognized format” errors that are caused by corruption and gives recovery guidance. (support.microsoft.com)

If those steps fail, capture: exact Access/Runtime build & bitness, the app process bitness, and the full error text. That info narrows whether it’s bitness/driver, an ACCDE version mismatch, or a corrupted file.

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Member Avatar for rproffitt

I'd get to the Microsoft forums on this one. Or just call it in.

is errily similar and what I'm finding are machines that are not current with service packs or updates.

-> Side note: This is partially why a new ransomware is spreading so quickly.

Member Avatar for John_162

Yes I Contacted Microsoft and yes there was a SP2 for the runtime.

Thanks

Edited by John_162
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