Symptoms

Captcha image is not loaded on the Blog page of site %domain.tld% . The following error appears in Apache log on the publishing host:

client denied by server configuration: /var/www/vhosts/%domain.tld%/httpdocs/resources/images/components/captcha.php

Cause

Apache modules mod_security , mod_evasive20 , PHP extension Suhosin or other security options are used on the publishing server (the server where to the site is published).

Resolution

Verify network settings, check logs, disable the modules on the publishing host.