This issue can be caused by corrupted cookies or cookies that are blocked. *check the permissions on the about:permissions page and in "Tools > Page Info > Permissions" *https://support.mozilla.org/kb/fix-login-issues-on-websites-require-passwords Clear the Cache and remove the Cookies from websites that cause problems. "Clear the Cache": *Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now" "Remove the Cookies" from websites that cause problems. *Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies" Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (3-bar button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem. *Switch to the DEFAULT theme: 3-bar button/Tools > Add-ons > Appearance *Do NOT click the "Refresh Firefox" button on the Safe Mode start window *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes ----- You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History > Show All History" or "View > Sidebar > History") or via the about:permissions page. Using "Forget About This Site" will remove all data stored in Firefox from that domain like bookmarks, history, cookies, passwords, cache, and exceptions, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note. You can't recover from this 'forget' unless you have a backup of the involved files. If you revisit a 'forgotten' website then data from that website will be saved once again.