Excel won't open file due to file format or file extension is not valid.

Question

I recently got a laptop in order to work from home and when I go to download a document from my works website, and open it in Excel, it displays, "Excel cannot open the file '(insert file name)' because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file."

I can open the downloads in Excel just fine when I am in the office.

Answer 1

Hi Jess,

Thanks for posting in the community. We are happy to help you.

According to your description, please try the steps in this article to Open and Repair the downloaded workbook in Excel, then check again.

If the error message still appears, as you mentioned it works well when you open it in the office, to troubleshoot whether the situation is caused by the workbook itself, please ask your colleagues to download the file from your work website, and then check again.

We look forward to your response. Thanks for your cooperation.

Sincerely,

George | Microsoft Community Moderator

Answer 2

I did not see what those steps told me to do. There was no open and repair option.

My colleagues can open their downloads just fine.

Answer 3

Hi Jess,

Thanks for posting back.

Please try the following steps to open and repair the workbook as shown in the screenshot below.

1. Run the Excel desktop app.
2. Click File> Open, choose "This PC", select the path and the File Explorer will pop on.
3. Go the related location and select the workbook. Click the down arrow beside the Open button and choose "Open and Repair".

For "My colleagues can open their downloads just fine.", I suppose you all download the same file for the work website. If not, please point it out and let us know (you don't need to try the following suggestions).

If so, the situation may be caused by your Office applications. Please try the following suggestions, then check again.

1. Please try to set Excel into Safe Mode.

Close Excel first, press Win + R, in the Run box, type excel /safe, and click OK. After that, please click File> Open to open the workbook and check again.

2. Please try to Repair Office and choose Online Repair. After that, please run Excel and check again.

If the above suggestions don't help, I would like to collect more information.

1. Does the situation only happen to this file or also happen to other online files?
2. Please provide your Office version.

Click File> Account, please take a full screenshot of the current interface. You can click the "Insert Image" button to upload it.

We look forward to your response. Thanks for your cooperation.

Sincerely,

George | Microsoft Community Moderator