1/9/26 25H2 Windows Update: Disabled usage of Microsoft Excel 97 Worksheets

Denise Webb 0 Reputation points
2026-01-12T12:39:21.0933333+00:00

The 1/9/26 25H2 Windows Update has disabled usage of all of Microsoft Excel 97 Worksheets on my laptop. I have tried changing settings in Protected View, Add Ins, File Block Settings. I have tried changing ext of files using a website to .xlsx files. I have ran my Anti Virus.

HELP! I don't know why this change would have been made. I need these files to do my job!!!

Moved from: <Microsoft 365 and Office | Excel | For business | Windows>

Microsoft 365 and Office | Excel | For home | Windows
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  1. AI answer

    2026-01-12T12:39:31.1233333+00:00

    It seems that the recent Windows Update may have affected the ability to open Microsoft Excel 97 Worksheets due to the File Block settings in Microsoft Office. To address this issue, you can try the following steps:

    1. Check File Block Settings: Open Microsoft Excel, go to the File tab, click on Options, then select Trust Center. Click on Trust Center Settings, and then navigate to File Block Settings. Ensure that the checkboxes for the file types you want to open (like Excel 97 Worksheets) are unchecked.
    2. Registry Changes: If the File Block settings do not resolve the issue, you might need to modify the registry settings to allow Excel 97 files. You can use the following registry script to enable opening of these files:
      • For Microsoft Excel 2007: 
             Windows Registry Editor Version 5.00
     [HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\Security\FileOpenBlock]
     "BinaryFiles"=dword:00000000
      • For Microsoft Excel 2010: You can also manually clear the checkboxes in the File Block Settings as mentioned above.
    3. Compatibility Mode: If the above steps do not work, consider opening Excel in compatibility mode or using the Microsoft Office Isolated Conversion Environment (MOICE) to open older file formats securely.

    If you have already tried these steps and are still facing issues, it may be beneficial to check for any additional updates or patches that may address this problem.

    References:

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  2. Anonymous
    2026-01-12T14:33:04.2966667+00:00

    Hi @Denise Webb, 

    Thank you for posting your question in the Microsoft Q&A forum.              

    Regarding that you can't open your Excel file. I’d like to ask a quick questions to better understand your situation and assist you effectively:      

    • What version of Microsoft Excel are you currently using?  (e.g., Excel 2016, Excel 365) 
    • I noticed you posted under the Business tag, so my guidance will focus on business accounts. If your issue is with a personal account, could you confirm that so I can adjust my steps? 
    • Are you receiving any specific error message when opening the file?  If yes, please share the exact wording. 
    • Could you provide a screenshot of the error?  (Feel free to hide any sensitive information.) 
    • What file type was that file save as?  (.xls, .xlsx, or another format?) 
      User's image
    • Where is the file saved?  Is it stored locally on your computer or on a SharePoint site/OneDrive? 

    Thank you again for your time and understanding. While my initial response may not resolve the issue immediately, I’d like to gather more details about your situation so I can assist you more effectively.           

    I really appreciate your patience, and I’m here to help. Looking forward to your response.          

    Wishing you and your family a joyful holiday season and a prosperous New Year.                          

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread 

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  3. Xavier-D 13,660 Reputation points Microsoft External Staff Moderator
    2026-01-13T11:24:16.3733333+00:00

    Hello Denise Webb,

    Thank you for posting your question on Microsoft Q&A forum

    I understand you can't open your Excel 97 worksheet (.xls file) on your Microsoft Home & Office 2021.

    Here is what you can try:

    Try using “Open and Repair” feature in Excel

    • Open Excel go to File > Open > Browse
    • Select the .xls file
    • Click the down arrow (▼) on the Open button
    • You should be able to see Open and Repair option, choose it.
    • Select Repair.

    If the file repair proves to be a success and you are able to open the .xls file, you should immediately save as .xlsx to convert them to newer format.

    If you still can't open the worksheet, consider using Office online repair too. There is also a possibility that this issue is cause by Excel itself. Please refer to this link for instruction on how to use online repair:

    https://support.microsoft.com/en-us/office/repair-an-office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b

    Feel free reply back to this post and update me on the situation, I'll be happy to assist you.

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