On a new cPanel server using SSL, occasionally you may see the following error:
This can be fixed by adding two lines into the server's apache configuration.
Log into WHM > Apache Configuration > Include Editor > Pre-virtualhost include
Add the following two lines at the bottom of the section:
SSLUseStapling on SSLStaplingCache shmcb:/tmp/stapling_cache(128000)
Then save and restart apache.