Where/how can I change this message?
<p>The server encountered an internal error or
misconfiguration and was unable to complete
your request.</p>
<p>Please contact the server administrator at
xxx to inform them of the time this error occurred,
and the actions you performed just before this error.</p>
<p>More information about this error may be available
in the server error log.</p>
</body></html>
or as a work-a-round, how can refuse access with modsecurity and just generate a 200 blank page response.
SecRule REQUEST_HEADERS:User-Agent "blockthisua" "id:'13006',phase:2,log,deny,status:200"