... I have no issues using Yahoo mail in Edge: all contacts show, I'm able to refresh the page or open 'compose' in a new tab without getting he redirect error and I get contact names when typing a name in "To" .

If clearing cookies doesn't help, it is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted.

• rename/remove cookies.sqlite (cookies.sqlite.old) and when present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder with Firefox closed in case cookies.sqlite got corrupted.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Does it still happen in Troubleshoot Mode?

I want to make sure I understand.. in the profile folder I should delete or rename cookies.sqlite and FF will generate a new one on restart? I did that but no change. If I refresh the page I get the same error... and no contacts. I have never had this issue until the refresh and as I said it works fine in Edge so it's not a Yahoo issue.

Thank you.

Does it still happen in Troubleshoot Mode?

I just tried in Troubleshoot and it works fine! Thank you.. I should've tried that first.. but I don't understand because I don't think I made any changes to my extension settings after the refresh (the same 2 extensions I had before) so i have no idea which setting it is. .

Does it still happen in Troubleshoot Mode?

I have figured out the issue - on reinstalling my adblocker I enabled a setting I didn't have enabled before the refresh and my Yahoo contacts are back and no cookie error message. It was the extension and not Firefox - thank you so much for the easy fix I should have thought of!