The user who invoked the message on the source database needs to exist and have the proper security on the target database. For example, if user SOMEONE is sending a message from HRMS to FSCM, then the UserID SOMONE must also exist on the FSCM side and have access to the service operation.
If the remote node on the source database is set to external (8.48-8.49) or in 8.50+ the service operation is exclude from PSFT Authentication, then the Default UserID set on the source Node defined on the target system is used.
PeopleSoft uses ANONYMOUS node when third parties are sending web services to PS and the ANY to Local Routing is defined. Again, the Default UserID needs to be valid and have access to the service operation.
Verify that the UserID that invoked the service operation on the source database has a User Profile defined and the account is not locked out on the target database. In all cases check not only the UserID that invoked the service operation but the Default UserID on the default local nodes, remote PIA nodes and the ANONYMOUS nodes. All these UserIDs defined must be valid User Profiles.