Created Unassigned: Exception when importing file [3212]

I have exported all my resx files in excel, in order to send the file for completing the translations.

Now the the file is fully translated, when I'm trying to import it back to my application I get an exception (see attachment).

I try to remove the comments column, but the exception remain the same.

My file contain one sheet for each resx.

When i'm making a file with only one sheet for one resx, the import works fine.


Any idea?