"Error 500" is reported by the WebMonitor agent when attempting to monitor a URL that is used for an application that is not Web based. The application expects an HTTP Post to send the transaction and credential to the application and then it returns a response.
"Error 500--Internal Server Error" is reported when attempting to access the URL with a browser also. A web page is not displayed after navigating to the URL from a browser and entering the credentials.
The following message is reported in the debug WebMonitor agent log.
2019-10-23 14:03:10.607 DEBUG [COLLECTION-ADDON-5] java.lang.Class - org.apache.http.wire:http-outgoing-840856 << "</FONT><P><FONT FACE="Courier New">The request requires user authentication. The response MUST include a WWW-Authenticate header field (section 14.46) containing a challenge applicable to the requested resource. The client MAY repeat the request with a suitable Authorization header field (section 14.8). If the request already included Authorization credentials, then the 401 response indicates that authorization has been refused for those credentials. If the 401 response contains the same challenge as the prior response, and the user agent has already attempted authentication at least once, then the user SHOULD be presented the entity that was given in the response, since that entity MAY include relevant diagnostic information. HTTP access authentication is explained in section 11.</FONT></P>[\n]"