Hi This issue is usually caused by corrupted cookies. Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences). "Remove the Cookies" for websites that cause problems: *Options/Preferences -> Privacy & Security<br>Cookies and Site Data: "Manage Data" "Clear the Cache": *Options/Preferences -> Privacy & Security<br>Cookies and Site Data -> Clear Data -> Cached Web Content: Clear If clearing cookies didn't help then it is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted. *rename/remove <b>cookies.sqlite</b> (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 -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the <b>about:profiles</b> page. *Help -> Troubleshooting Information -> Profile Folder/Directory:<br>Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder *https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data