Closing as duplicate. Please see and continue from [/questions/1159563#answer-967007] -J99 Hi Firefox, Please help me to get rid of connection secure error"SEC_ERROR_UNKNOWN_ISSUER" I tried all solutions available in internet example: replacing cr8.db, deleting cr8.db and copy from another computer to non working computer, refreshed going to the trouble information window, antivirus m using eset and that SSL security web and email options disabled the secure scanning also disabled,completely uninstalled deleting all the firefox files in computer, even i deleted mozilla files in %appdata% and restarted Pc and installed again..... everything i tried still m not able to get rid of connection secure error "SEC_ERROR_UNKNOWN_ISSUER" .... Please please help ASAP. I hope firefox will resolve my issue ASAP. Thanks &Regards Mahantesh