Symptom
When We register java system to monitoring from RZ21
Choose Technical Infrastructure → Configure Central System → Create Remote Monitoring Entry
we must define HTTP Port of the Message Server.
When We try set HTTP Port of the Message Server 50000, or 3901, We have error
No valid XML document received. ( http://hostname:50000/msgserver/xml/logon )
Solution
Set HTTP Port of the Message Server to 81XX