I uninstalled Firefox and reinstalled. Same problem. I Refreshed Firefox. Same problem.

I see the problem with that link, and this is something that probably needs to be fixed on the server.

The first screen shot shows that Firefox thinks it is a PDF and that its name is Denon, to which Firefox is going to add .pdf. This is not what the site intended.

The second screen shot shows the source of the confusion. The site is informing Firefox that the file is application/pdf, which is why Firefox think it is a PDF. The site is sending a filename that ends with .xlsx BUT it is sending the file name with spaces. Firefox only reads to the first space and truncates the file name.

Ideally, the site would fix both of those things. However, simply fixing the spaces would give you the behavior of Chrome, which is to save the file with its intended extension even though the site said it is a PDF.

I can't recall whether there is any workaround/add-on for this on the browser side (to force Firefox to read past the first space in the filename parameter).

Appreciate the helpful response!! I contacted Denon with your recommendations and hopefully they will resolve on the server side to avoid this problem in the future.

One thing I do see quite often is that FireFox usually seems to have the most trouble with attachments, opening PDF's, etc. and Google Chrome seems to be the most reliable. I prefer Firefox and use it as my default, but I find myself using Chrome when I run into the above type issues.

Thanks again for the help!!

I don't know how to feel about it. Mozilla often doesn't fix things when the problem is that websites do not follow proper techniques, to push developers to become more standards compliant. IE and Chrome have more of an attitude that they will protect users from some incorrect practices even if that allows sites to be a bit lazy. When more people used Firefox, I think Mozilla's way was helpful and had the intended effect, but now, I wonder whether it still is/does.