On Plesk server, i get following error on error_log for a site
[Tue Apr 23 08:50:32.336220 2019] [core:alert] [pid 30457:tid 140337888573184] [client 86.243.163.203:44805] /var/www/html/.htaccess: Invalid command 'AuthGroupFile', perhaps misspelled or defined by a module not included in the server configuration
This is because authz_groupfile apache module was not loaded. To load this, run
a2enmod authz_groupfile service apache2 restart
To verify the module is loaded, run
root@root1313:~# apachectl -M | grep auth auth_basic_module (shared) auth_digest_module (shared) authn_core_module (shared) authn_file_module (shared) authz_core_module (shared) authz_groupfile_module (shared) authz_host_module (shared) authz_user_module (shared) root@root1313:~#