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How to Fix Excel Automation Error 0x80040154 in Windows 11

Is your Microsoft Excel crashing with "Automation Error: 0x80040154" today? On January 25, 2026, a massive wave of spreadsheet failures has hit office workers worldwide following a silent update to the Windows AI Core components. The error code "0x80040154 (Class not registered)" is preventing users from opening macro-enabled workbooks (.xlsm) and accessing external data links. If your business spreadsheets are locked behind this error, here is the first verified guide to repairing your Excel environment immediately.

​What Causes Excel Error 0x80040154 in 2026?

​The 0x80040154 error is a "Registry Misalignment" issue. In the January 2026 Windows update, Microsoft modified the way COM (Component Object Model) objects are registered to accommodate new AI features. This has inadvertently "unregistered" the core Excel libraries used for automation and macros. Unlike standard Office reinstallation, this fix requires a manual re-registration of the system's DLL files to restore the connection between Excel and Windows.

​4 Verified Fixes for Excel Error 0x80040154 (January 2026)

  1. ​Manual Re-registration of OLE Automation:
    • ​Right-click the Start button and select Terminal (Admin).
    • ​Type the following command and hit Enter: regsvr32.exe C:\Windows\System32\ole32.dll
    • ​You should see a "Succeeded" message. This manually re-links the core automation engine that the 2026 update disconnected.
  2. ​The "FM20.DLL" Library Fix:
    • ​This error often occurs because of a corrupted form library. Navigate to C:\Windows\SysWOW64\.
    • ​Find the file named FM20.DLL. If it is missing or renamed, Excel will throw the 0x80040154 error.
    • ​Copy it from a backup or use the Microsoft Office Repair tool specifically for "Shared Components."
  3. ​Disable "Copilot Excel Integration" (Temporary):
    • ​Open Excel (if possible) and go to File > Options > Add-ins.
    • ​At the bottom, select COM Add-ins and click Go.
    • ​Uncheck "Microsoft Copilot AI for Excel".
    • ​This new 2026 feature is the primary cause of the Class Not Registered conflict.
  4. ​Fix the Registry Path (Advanced):
    • ​Press Win + R, type regedit.
    • ​Go to: HKEY_CLASSES_ROOT\TypeLib\{00020813-0000-0000-C000-000000000046}.
    • ​If you see a version folder like 1.10 or 1.11, ensure the "PrimaryInteropAssemblyName" points to the correct 2026 Office build. If you find a "dead link" here, delete the sub-key and restart Excel.

​Official Support Status

​Microsoft’s enterprise support has acknowledged a "Library Registration Conflict" for Office 365 users on the 2026 Windows 11 builds. While a global patch is scheduled for early February, the regsvr32 ole32.dll method is currently the only confirmed way to restore macro functionality for accounting and finance departments today.