Does it still happen in Troubleshoot Mode?

Hi Thank You for responding I am a novice with computers , I tried downloading them again in troubleshoot mode and I refreshed Firefox but it is still reading as undefined , It is frustrating as I used to download ebay PDF's and they would open no problem but for the last 2 months they won't yet all other PDF's download and open no problem , I have also noticed that past ebay PDF's were approx 590kb but the undefined ones are downloading at approx 393b

You can create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works, you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Try disabling Tracking Protection for the site.

Are you able to share a link to an ebay page with a PDF where you encounter this?

Hi Cor-el thank you for your response I looked into setting up a new profile but as a novice I am frightened I would only make things worse , I am currently having problems with my settings on firefox, every time there is an update it throws all my settings out and I have to go through them one by one to reset them , either my font is too small or my page size is too large and my toolbars are too large , it is very frustrating trying to get settings you are comfortable with then an update puts you back at the beginning, Anyway your suggestion was appreciated and I thank you for it

Hi Zeroknight once again thank you for your assistance and your suggestion I did try disabling Tracking Protection for that site but unfortunately it still didn't work I have tried copying and pasting a screenshot of the issue and again I have been unsuccessful

Does it still happen in Developer Edition?