How to Fix Microsoft 365 Cannot Open Excel 97 XLS Files
Question details
The user needs to open legacy Excel 97 (.xls) workbooks in Microsoft 365, but the application unexpectedly closes or actively blocks the files.
- Product
- Microsoft 365
- Device & OS
- not provided
- Scenario
- Attempting to open old .xls spreadsheets created in Excel 97 or earlier versions within a modern Microsoft 365 environment.
- Observed behavior
- Microsoft Excel crashes, closes unexpectedly, or actively blocks the legacy file formats from loading upon attempting to open them.
Create a safe backup copy of your original .xls file before attempting any repairs, and never manually rename the file extension from .xls to .xlsx, as this can cause irreversible file corruption.
Disable File Block Settings in Excel Trust Center
Microsoft 365 proactively blocks older file formats for security reasons. Adjusting the Trust Center settings allows these legacy files to open.
By default, modern versions of Microsoft Excel block Excel 97 and Excel 2003 binary formats to protect your device from potential macro vulnerabilities. If you trust the source of the file, you can temporarily disable this block in your security settings.
Launch Microsoft Excel, click on the 'File' tab in the top-left corner, and select 'Options' located at the bottom of the left-hand menu.
In the Excel Options window, select 'Trust Center' from the left sidebar, then click the 'Trust Center Settings...' button.
Select 'File Block Settings' from the left pane. Locate 'Excel 97-2003 Workbooks and Templates' in the list and uncheck the 'Open' and 'Save' boxes, then click 'OK' to apply the changes.
Open the File Directly Within Excel Using Open and Repair
If double-clicking the file from your file explorer causes a crash, opening it directly through Excel's built-in repair tool can bypass the error.
Open Legacy Excel Files Seamlessly with WPS Office
If Microsoft 365 continues to crash or you prefer not to lower your application security settings, WPS Spreadsheet is a highly compatible and lightweight alternative. It opens legacy .xls formats instantly without requiring complex workarounds or triggering file blocks.
- 1. Install WPS Office: Download and install the free WPS Office suite on your computer.
- 2. Select the File: Locate your legacy Excel 97 .xls workbook in your file explorer.
- 3. Open with WPS: Right-click the file, select 'Open with', and choose 'WPS Spreadsheets' to view your data immediately.
Frequently Asked Questions
Why does Microsoft 365 close unexpectedly when opening an .xls file?
Microsoft 365 may crash or close if the legacy file is corrupted, contains outdated macros that conflict with modern security protocols, or if it is restricted by the Trust Center's File Block Settings.
Can I fix the compatibility issue by changing the file extension to .xlsx?
No. Simply renaming an .xls file to .xlsx changes the name but not the underlying file structure. This will corrupt the file further and make it completely unreadable by any spreadsheet software.
How do I safely convert an Excel 97 file to a modern format?
Once you successfully open the file using either Trust Center adjustments or an alternative like WPS Office, navigate to 'File' > 'Save As', and choose 'Excel Workbook (*.xlsx)' from the format drop-down menu to securely upgrade the format.
