The Microsoft.ACE.OLEDB.12.0 provider is part of the Microsoft Access Database Engine. To use it in both 32-bit and 64-bit environments on the same machine, you typically need to install the Microsoft Access Database Engine 2010 Redistributable or the newer 2016 Redistributable using a command-line workaround, as Microsoft generally prevents installing both bitness versions through the standard interface. Official Download Links

To bypass Office version mismatch (advanced):

Add the /passive switch to see progress, but it still may fail if Office bitness differs. The only workaround for a mismatch is to install the "Microsoft Access Database Engine 2016 Redistributable" using the /quiet switch, which sometimes ignores the conflict (not guaranteed).

Option 1: The Correct Download (Recommended)

Microsoft has replaced the standalone "AccessDatabaseEngine.exe" with the Microsoft Access Database Engine 2016 Redistributable.

Run the Installer with the /passive switch. For example, to force the 64-bit installation while 32-bit is present, navigate to your download folder and run: accessdatabaseengine_X64.exe /passive.

Access 2016 Engine (Provider 16.0): Download 2016 Redistributable. Microsoft 365 Runtime: Download M365 Access Runtime. Key Troubleshooting Tips Microsoft Access Database Engine 2016 Redistributable

Step 1: Install the 64-bit version first (as usual)

1. On the download page, look for the download files.
2. Select AccessDatabaseEngine_X64.exe. This is the 64-bit specific version.
3. Download and save the file.

“The ‘Microsoft.ACE.OLEDB.12.0’ provider is not registered”
→ Install the matching bitness version for your application. A 64-bit app cannot load a 32-bit provider.

Note: Both files are listed on the same Microsoft download page. Look for the "Choose your download" section and select the appropriate version.