To fix the “Excel file format and extension don’t match” error, first check if the file extension matches its format. Try renaming the file with the correct extension (e.g., .xlsx for Excel ...

If the file opens in read-only mode, you may still make changes and use the "Save As" command to save the file to a new name. Save the file in the Excel 2003 or 2007 format, but with a different name.

With Office 2007, Microsoft introduced entirely new file formats for Word, Excel, and PowerPoint. Designated by an x at the end of the file extension (.docx instead of .doc, and so on), these were ...

Microsoft has pledged to make its new Office 2007 file formats accessible within the company's other products, but the timeline for that support varies widely. Although the company already has ...

Microsoft Excel lets you format tables, adding borders and colors, and lets you format the text in them, editing font, size and style. ... How to Copy to a New File in Excel.