Error “cannot load certificate” when changing SSL certificates in ispmanager 6

Symptoms

When attempting to change the SSL certificate in the site settings in the ispmanager 6 panel, the following error message is displayed:

"An error occurred while working with the websites. An attempt to test configuration of the web-server while saving the file '/etc/nginx/vhosts/<username>/<site_name>.conf' failed: nginx: [emerg] cannot load certificate "/var/www/httpd-cert/<username>/<certificate_name>".

Causes

An invalid certificate is being used for the site.

Solution

Relocate the malformed certificate files to an alternative directory, e.g. "/root":

mv /var/www/httpd-cert/<username>/<certificate_name>.* /root/