Several months ago, I couldn't log in to my Yahoo email accounts. For reasons yet to be explained, the two step verification ended up with a message saying they were having trouble, and try again later. No amount of waiting for later worked. Maybe what I'm asking about now is unrelated, but yesterday I tried again. When I go here [https://www.yahoo.com/ Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports ], and select either of the links [https://i.postimg.cc/m2GxQM1h/yahoo4.jpg link text] I am directed here [https://i.postimg.cc/jqH3Y1Cd/yahoo2.jpg link text] [https://signin.att.com/dynamic/iamLRR/LrrController?IAM_OP=login&appName=m40842&loginSuccessURL=https:%2F%2Foidc.idp.clogin.att.com%2Fmga%2Fsps%2Foauth%2Foauth20%2Fauthorize%3Fnonce%3DJOI1J9M8tM%26SPRelayState%3Dhttps%25253A%25252F%25252Fmail.yahoo.com%25252Fd%26redirect_uri%3Dhttps%253A%252F%252Fatt-yahoo.att.net%252Fisam%252Fsps%252Foidc%252Frp%252FATT-HBO-RP%252Fredirect%252FYahoo%26response_mode%3Dform_post%26scope%3Dopenid%26response_type%3Did_token%26state%3DDkTBOU3QQm%26ForceAuthn%3Dfalse%26client_id%3Dm40842 link text] Instead of here (these came from Chrome) [https://login.yahoo.com/manage_account?pspid=159600001&activity=mail-direct&.lang=en-US&.intl=us&src=ym&signin=true&done=https%3A%2F%2Fmail.yahoo.com%2Fd&eid=100 Welcome to Yahoo Mail] https://i.postimg.cc/c45Qp77L/yahoo5.jpg When I use that url in Firefox, I am taken here [https://i.postimg.cc/85t2DnPY/yahoo6.jpg link text] If I try to add a Yahoo account in that situation, it becomes clear that IS only for adding other other AT&T accounts. I tried using '''about:support - Troubleshooting Information''' to clear the startup cache, and in safe mode, but it did not help. I talked to ATT&T. They have been having these sorts of Firefox related problems for months now, which they have reported to Mozilla month ago (which confirms my past troubles as well), but for whatever reason Mozilla hasn't acted on it. But here is the weird part for me. Aside from my main profile, I have a Firefox "basic" profile. It has no addons, but It has basically the same settings with my main profile, and, because it hasn't been updated in a while, I believe it has '''most '''of the same about:config tweaks as well. In that profile, It 'Yahoo ''works '''. What could constitute a difference between this starter profile and one that's running in safe mode to create this problem. Can you think of an about:config tweak that could be responsible for all this? Do we have any idea whats causing this.