Fixing “The provider ‘Microsoft.ACE.OLEDB.12.0’ is not registered” (Driver errors).

This error occurs when Excel, Power Query, or an external script attempts to connect to an Access database (.accdb, .mdb) or an Excel file using an Object Linking and Embedding Database (OLE DB) provider that is not installed or has a bitness mismatch with your operating system.

Quick Answer

Download and install the Microsoft Access Database Engine Redistributable. You must match the bitness of the driver to your version of Microsoft Excel (install the 64-bit driver for 64-bit Excel, or the 32-bit driver for 32-bit Excel). If the installer blocks installation due to existing Office components, run the installer from the Command Prompt with the /quiet switch.

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What Causes the ACE Provider Error

The Microsoft Access Database Engine (ACE) is the background driver suite Microsoft provides to read and parse Access databases, text files, and legacy Excel workbooks. The identifier Microsoft.ACE.OLEDB.12.0 originally shipped with Office 2010/2007, while Microsoft.ACE.OLEDB.16.0 corresponds to Office 2016, 2019, and Microsoft 365.

This error is almost always caused by one of two scenarios:

1. Missing Driver: The machine does not have the standalone Access Database Engine installed.
2. Architecture Bitness Mismatch: You are running 64-bit Excel, but only the 32-bit ACE driver is installed (or vice versa). A 64-bit application process cannot load a 32-bit DLL driver into its memory space.

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Step-by-Step Diagnostic and Resolution Path

Step 1: Check Your Excel Bitness

Before downloading any installer, verify the exact bitness of your running Excel instance:

1. Open Excel.
2. Go to File > Account.
3. Click the About Excel button.
4. The very first line of the pop-up window lists the version number followed explicitly by either 32-bit or 64-bit.

┌────────────────────────────────────────────────────────┐
│  About Microsoft® Excel® for Microsoft 365             │
├────────────────────────────────────────────────────────┤
│  Microsoft® Excel® for Microsoft 365 MSO (Version ...) │
│  64-bit ◄───────────────────────────────────────────── │
└────────────────────────────────────────────────────────┘

Step 2: Download the Matching Redistributable

Navigate to the official Microsoft Download Center and download the Microsoft Access Database Engine Redistributable (available for version 2010 or 2016):

• If your Excel is 64-bit, download: accessdatabaseengine_X64.exe
• If your Excel is 32-bit, download: accessdatabaseengine.exe (the x86 version)

Run the installer and follow the setup wizard. Once completed, restart Excel and re-test the connection.

Step 3: Overriding the Side-by-Side Installation Block

A common roadblock occurs when you run 64-bit Office, but the installer detects residual 32-bit components (or vice versa), displaying this message:

“You cannot install the 64-bit version of Microsoft Access Database Engine because you currently have 32-bit Office products installed.”

To bypass this check and force the engine to install:

1. Open the Windows Command Prompt as Administrator (search for cmd, right-click, and select Run as administrator).
2. Use the cd command to navigate to the folder where you downloaded the file (for example, your Downloads folder): cd C:\Users\YourUsername\Downloads
3. Run the installer with the /quiet flag:(Replace with accessdatabaseengine.exe /quiet if installing the 32-bit version). accessdatabaseengine_X64.exe /quiet
4. The installer will run silently in the background without raising the side-by-side architecture conflict. Wait approximately 60 seconds, then check your Task Manager to ensure the installer process has completed.

Step 4: Verify the Registry Registration

To confirm the driver is properly registered in Windows:

1. Press Win + R, type regedit, and press Enter.
2. Navigate to: HKEY_CLASSES_ROOT\Microsoft.ACE.OLEDB.12.0
3. If this key exists, Windows recognizes the provider.
4. If you see Microsoft.ACE.OLEDB.16.0 instead, your system is using the newer Office 365/2016 engine. Update your connection string or M-code to point to Microsoft.ACE.OLEDB.16.0 instead of 12.0.

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Migrating to Native Power Query Connectors

If you encounter this error in Power Query while using a custom OLE DB or ODBC connection string to read an Access database or local Excel workbook, replace the connection with Power Query’s native connectors.

• Instead of using OleDb.DataSource("Provider=Microsoft.ACE.OLEDB.12.0;..."), use:
  or for Excel files: Source = Access.Database(File.Contents("C:\Database\Inventory.accdb")) Source = Excel.Workbook(File.Contents("C:\Data\Source.xlsx"))

Native connectors handle their own internal data parsing routines and do not depend on legacy system OLE DB registrations.

For related driver registration errors across mixed office environments, see Fixing “Microsoft.ACE.OLEDB.16.0 provider is not registered” for Access/SQL hybrids and Fixing “Automation Error: Library not registered” in mixed 32/64-bit environments. For VBA-specific bitness adjustments, consult 32-bit vs. 64-bit: Fixing “The code in this project must be updated for use on 64-bit systems.”