Legacy XLSX once modified in 2011 cannot be re-openend

[wildcatherder]

We are having a problem reopening saved XLSX (as well as DOCX) files.

If a legacy XLSX file (probably from Excel 2009 for Mac) is opened in Excel 2011 for Mac, modified, then saved, it become un-openable.

Error message is:
"Excel cannot open this file. 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"

Since the filename nor extension has been changed, the only source of "corruption" is Excel 2011 itself.

Note that saving to an even older legacy format XLS does allow the file to be reopened.

Has anyone had this problem AND found a solution?

 

[wildcatherder]

We have traced the problem to metadata fields which are used by the Mac version but not created by the Windows version.

There is a Type field which is not created by Windows versions. By default, Excel 2011 appears to set this to 'XLS8" when a Windows version file is opened, then saved in Mac 2011, even though the file type extension is XLSX. (This is a holdover from the days when Mac versions ignored extensions and only used metadata fields to identify file formats) Excel 2011 cannot resolve the conflict between the field and the extension when it comes time to reopen; the file refuses to open - "Excel cannot open this file".

The solution is to open the Windows-created file in Excel 2011 and immediately save it in XLS format. At that point the file type field "XLS8" and the extension will agree. Reopen the file in Excel 2011 and save it as XLSX. Again, the Type field "XLSX" will agree with the file extension and the file can be used normally from then on.

There may not be a lot of people importing Windows files to Excel 2011 but they will be glad to find an answer to this problem. We were fortunate in having the Pathfinder program which allowed us to view the Type field, which is not visible using "Get Info" in FileFinder.

 

[Cindy Ellis]

Thank you for posting the solution. It may not be a problem that's encountered frequently (hence no replies from the gurus here), but the fact that you found a solution and have shared it is helpful.
Cindy

 

[wildcatherder]

I should note there is a similar problem and solution involving DOCX format in Word 2011 for Mac.