Error Code :ssl_error_weak_server_ephemeral_dh_key firefox

For solving this  ssl_error_weak_server_ephemeral_dh_key type "about:config" on your firefox..

Then press enter...

On the search box type "security.ssl3" as shown below :

Next... Change the value of security.ssl3.dhe_rsa_aes_128_sha and security.ssl3.dhe_rsa_aes_256_sha to false.....

Aaand... you are good to go.. you don't have to restart your firefox ... :-)
But as a little information, change those values will decrease the encryption level of our connection to server so the third parties (harckers) can listen or steal our information. So if you face this issue, please tell the administrator of the server to fix this issue on it's server... :-)