Files not opening in microsoft 365 saying corrupt or extension invalid but had previously opened

Hi Alfie,

Thank you for using Microsoft products and making community posts.

I understands the importance of resolving this issue, Don’t worry I will be helping you with this following steps.

Possible Fixes

1. Try Opening in Office Online – Sometimes, opening the file in Office Online instead of the desktop app can bypass corruption issues.
2. Check File Properties – Right-click the file, go to Properties, and ensure it’s set to open with the correct version of Word or Excel.
3. Disable Protected View – Open Word or Excel, go to File > Options > Trust Center > Trust Center Settings > Protected View, and uncheck all options.
4. Use Open and Repair Again – Try opening the file using File > Open > Browse, then click the arrow next to Open and select Open and Repair.
5. Convert the File Format – If the file is .doc or .xls, try converting it to .docx or .xlsx using an online converter or Office Online.
6. Check OneDrive Sync Issues – If OneDrive files are also affected, try pausing OneDrive sync and manually downloading the file before opening it.

Please feel free to let me know how it goes.

Chan G

Microsoft Community Moderator

Hi

Thanks for the response.

I have tried all options and all have the same result unfortunately, with no change

Thanks

Alfie

Looking on line it seems loads of people are having this issue but no one can come up with a solution!

Hi Alfie,

Thank you for your response.

Were you able open these files on OneDrive online?

Are all of the files are affected?

While waiting for your response, try these other steps below:

1. Try Opening in Another Program

• If your file is an Excel file, try opening it in Google Sheets or LibreOffice Calc.
• If it's a Word document, try opening it in Google Docs or WPS Office.
• If these programs open the file, you may be able to save it in a new format.

2. Check for Temporary Versions

• Open File Explorer, go to %AppData%\Microsoft\Excel\ or %AppData%\Microsoft\Word.
• Look for autosaved versions and try opening them.

3. Use Microsoft’s File Recovery Tool

• Microsoft offers a recovery tool for damaged Office files. Download it here.

4. Convert the File Format

• Try renaming the file extension: .xlsx → .csv (for Excel) .docx → .rtf (for Word)
• Then attempt to reopen it.

5. Open in Safe Mode Again (But With New Steps)

• Close all Office apps.
• Hold Ctrl while opening Excel or Word.
• Try opening your file again in Safe Mode.

Chan G

Microsoft Community Moderator

Hi

Thanks for the response.

Its only random files that it happens to. Was originally only ones originating in old excel versions but now even ones that opened oK on onedrive (word & Excel) randomly have the error.

I have tries all steps and still no joy

Thanks