I generated a certificate.
$plugin->release = "3.0 (Build: 2015111601) Certificate
$release = '3.0.3 (Build: 20160314) Moodle
The error log says: error: directory is writable by others; mod/certificate.
These are the current permissions. On my previous attempt, I changed the permissions to the permissions on my old moodle with a working certificate. It didn't help, so I started over.