I know this has been discussed before. But I have been through everything. The file went from uploading no problem to error when nothing had changed.
I'm also wondering why the error message is so general now - in the past once before I got an error message specifying that the invalid character was a '+' that had been put in front of a phone number. That was easily fixed.
I have gone through everything and cannot find any invalid characters.
Any suggestions for finding and fixing please?