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 *Create a cookie 'allow' exception to keep such cookies, especially in case of secure websites and when cookies expire when Firefox is closed. *Tools > Options > Privacy > "Use custom settings for history" > Cookies: Exceptions This can also be stored in local (DOM) storage or in a Flash cookie. In case you are using "Clear history when Firefox closes": *do not clear the Cookies *do not clear the Site Preferences *Tools > Options > Privacy > Firefox will: "Use custom settings for history": [X] "Clear history when Firefox closes" > Settings *https://support.mozilla.org/kb/remove-recent-browsing-search-and-download-history Clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, passwords, and other website specific data. ---- Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem. *Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance *Do NOT click the Reset button on the Safe Mode start window *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes