Hey,
this topic reappears in 1.3.3, although it should be fixed:
_"Zend OPcache API is restricted by "restrictapi" configuration directive"
in
user/plugins/admin/themes/grav/templates/register.html.twig
TWIG{% embed 'partials/register.html.twig' with {title:'Grav Register Admin User', classes:'wide'} %}
Cache is disabled in system/config/system.yaml.
This is on a shared hosting so Zend is beyond our control.
(more references had to be removed because of discourse's limitation for new users)