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Texan's avatar
Texan
Copper Contributor
Jan 14, 2025

Annoying message when launching Excel...

Every time I launch Excel in Microsoft 365 I get the annoying message "Excel cannot open the file Book 9.xlxs because the file format or file format is not valid.  Verify that the file extension matches the format of the file and that the file has not been corrupted."

The Book number increments by one each time I launch Excel.  Clicking on "OK" gets rid of the message, but the whole thing is still annoying.

excel

4 Replies

  • HansVogelaar's avatar
    HansVogelaar
    MVP
    Jan 15, 2025

    If you are on Windows:

    • Quit Excel.
    • Start File Explorer.
    • Type or paste the following in the address bar, then press Enter:
    • %appdata%\Microsoft\Excel\XLSTART
    • If you see any file in the XLSTART folder except for one named PERSONAL.XLSB (or just PERSONAL), delete it or move it out of the XLSTART folder.
    • Start Excel again.
    • Does the problem still occur?

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