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Excel file won't open

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Every now and then, when I try opening an Excel file, I get a message saying that "Excel cannot open the file 'file.xlsx' because the file format or the file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file." Please see attached image.



Excel Ninja
Hi ,

What kind of help are you expecting ?

If you can upload one of these files which is giving you an error , we can try opening it and report back.

Either the file has been really corrupted or the message is a spurious one ; the best way is for others to try opening it.

See if these links help :





Excel Ninja
I have seen this message being thrown up sometimes when the files are not built in native Excel but are exports (xml based) from other software say pdf converter which export in xml but keep xls or xlsx extension.


Excel Ninja
Staff member

Firstly, Welcome to the Chandoo.org Forums

Backup the file first
Open Excel
Goto File Open
Browse and find your file, Select it but don't do anything yet

Click the small drop down next to the Open Button
Then Select Open and Repair

You should try and use the latest version of Excel you can get hold of
As they have been improving this functionality over time


New Member
In Excel 2003 VBA (and earlier), if you specify the file extension in the Workbook.Save method, then it will be saved as expected.

In Excel 2007 VBA (and later), you need to specify both the file extension and the file format. If you don't, you may succeed in creating a file with a .xls or .xlsm format--but .xlsx extension. I've made this mistake myself on a number of occasions. If so, renaming the file with the correct extension (while Excel is not running) will make it openable.

If the above trick does not work, then it is likely that the file is corrupted--such as if part of the content is missing. In such cases, I have never had success in opening the file using OpenOffice or Libre Office.
My best recourse has been to use an older copy of the file and recreate it. Or even if it doesn't work, then it really helps one excel file repair tool, such as Excel Repair Kit. It neatly and efficiently recovers data from the file and then saves it in the desired format.


New Member
Hi Reijo,

This is a very common error and it usually occurs due to incompatibility between the excel files and versions.

I suggest you try to change the Excel File Permissions.
Basically, the objective of doing this is to provide you with all the permissions of the file if you don't happen to have them.

1. Right-click on that excel file > properties
2. Go to the security tab and click on "edit"
3. when the permissions dialog box opens, click on "add"
4. Click on Advanced > Find Now
5. Under the search results, scroll down to "Everyone" and click on OK
You will see the "everyone" in the Textbox
6. Click on Ok again (and you will return back to the permissions dialog box)
7. Under Group or User names, select "Everyone" and check all the boxes under "Allow"
8. Click on Apply and then OK

Now try opening your excel file. I hope this will fix it.

Best Regards.
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