When downloading a file, if the filename has no extension, Firefox adds ".html" to the filename. I want it to leave the filename as-is, with no extension. It will leave the name intact if I surround it with quotation marks, but it didn't previously require this. Firefox Settings relates to Firefox extensions, which is not this issue. And the list of Applications does not include names that don't have an extension. Example of situation: An SSL Certificate site needs to confirm my ownership of a domain. I download a file from the issuing site. The file's name has no extension. Firefox adds ".html", which causes the file to be not found after uploading. Firefox did not have this misbehavior before the most recent update.