Hi Rhonda, that doesn't sound right. Is it fully converted to a PDF (you can view it in Preview) or is Firefox changing the file name extension from .xlsx to .pdf when it shouldn't?

Its mostly when I try to export a report from Quickbooks online to and excel sheet. It just automatically converts it to a pdf. Doesn't give me a chance to tell it what to do. I had chatgpt make me an excel template. When I clicked on the link it just automatically converts it to a pdf. I want it to open in excel not as a pdf. This all changed probably a few months ago. Was working fine before. I am using a Mac by the way. .

If you try to view the "PDF" files in Preview, does it say they are valid files? Presumably not.

If they are not valid PDF file, it could be a problem with Firefox changing the file extension to .pdf. Does Finder have a way to rename a file extension from .pdf to .xls or .xlsx (depending on the format)? If so, do they open in Excel?