Common causes include manually changing the extension without converting the file type, file corruption, or a security block from Excel’s Protected View. Now that you know the causes, lets discuss the solutions.
1. Change the Extension Manually
When the file extension doesn’t match the format, changing it manually helps Excel read the file correctly. Adjusting the extension (e.g., from .txt to .xlsx) aligns the file with Excel’s expectations. This won’t fix corrupted files, so ensure you identify the right extension.
2. Unblock the File (if Applicable)
Sometimes, Excel blocks files from unknown sources, causing the “File Format and Extension Don’t Match” error. Unblock the file in its “Properties” menu to let Excel open it. This action helps Excel access the file’s content by removing the security block.
3. Open the File with a 3rd Party Equivalent
Sometimes, Excel blocks files from unknown sources, causing the “File Format and Extension Don’t Match” error. Unblock the file in its “Properties” menu to let Excel open it. This action helps Excel access the file’s content by removing the security block.
4. Disable Protected View
Disabling Protected View in Excel lets you open files that are usually blocked for security reasons. This gives Excel full access to the file, useful if it wrongly flags safe files. Ensure the file is from a trusted source, as this action removes a security layer. Note: The steps below should work for Excel 2010 and newer versions.
5. Suppress the Warning Message
Suppressing the warning lets Excel open the file without checking for format mismatches. This is useful if you trust the file and want to avoid repeated alerts. It keeps your work flowing, especially with files from external sources or older Excel versions.
