Verify local Help content is installed. Verify you are able to get local Help content, and that the 500 error is specific ...

Verify local Help content is installed.  Verify you are able to get local Help content, and that the 500 error is specific to a topic and not a system error.  If you are not able to see any local Help content, then remove and re-install your content.  If the 500 error is specific to a topic, and if you know the book the topic was installed from, then try re-installing the source.