I got following error from the cpanel error log.
Internal Server Error: "GET /cpsess2130683265/3rdparty/roundcube/index.php HTTP/1.1" 500 No response from subprocess (php): The subprocess died from signal 11 (SEGV).
Internal Server Error: "GET /cpsess2130683265/3rdparty/roundcube/index.php HTTP/1.1" 500 No response from subprocess (php): The subprocess died from signal 11 (SEGV).