Hi, Please try this: open '''Help''' (or '''Alt''' + '''H''') > '''Troubleshooting Information''' > '''Open Containing Folder''' and delete the file named '''sessionstore.js''' or '''sessionstore'''. Please note that this will delete the restore information for all the tabs. ............................................................................................................................... Useful links: [https://support.mozilla.com/en-US/kb/Options%20window All about Tools > Options] [http://kb.mozillazine.org/About:config Going beyond Tools > Options - about:config] [http://kb.mozillazine.org/About:config_entries about:config Entries] [https://addons.mozilla.org/en-US/firefox/addon/whats-that-preference/ What's That Preference? add-on] - Quickly decode about:config entries - After installation, go inside about:config, right-click any preference, enable (tick) MozillaZine Results to Panel and again right-click a pref and choose MozillaZine Reference to begin with. [https://support.mozilla.com/en-US/kb/Keyboard%20shortcuts Keyboard Shortcuts] [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions/Add-ons] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes]