until a fw weeks ago I exported my gradebooks in exel spreadsheed format. Now suddenly, when I try to do it, the exel spreadsheet is downloaded but I can't open it. I get the message: invalid extension or format. This happens in every course.
I menaged to download the gradesreport as a plain text file, but doing this I have to convert it, and the exel spreadsheet was easier for me.
Does somebody knows, what could have happened?
I didn't change anything in my site. I tried to download the file from different computers.
I hope that someone is able to help me.