Hi,
I have the same problem and i correct it with the following instructions:
1.- Enter in the shell
2.- Go to the /etc/httpd :
cd /etc/httpd
3.- Generate new CSR (You may introduce a CN and the other data as you wish):
openssl req -new -key server.key -out server.csr
4.- Sing the CSR:
openssl x509 -req -days 1500 -in server.csr -signkey server.key -out server.crt
5.- At last, restart the HttpServer:
/etc/init.d/httpd restart
Now, try to acces to the GUI.
Many many thanks... After 4 years your post help me now to solve finally the certificate issue. Deleting certs on firefox doesn't help me, I created new certificate, and now I'm able again to login into firewall GUI with firefox!