We are receiving various "5025 Incompatible encryption type" errors, e.g.:
"Aug 28 15:22:46 hostname1 pmmasterd5.5.2 (051): 5025 Incompatible encryption type-please check pm.settings on remote host:hostname2"
The error may occur when the pmloadcheck daemon on a 5.5 agent tries to ping a master that's on an earlier version.
Can you intentionally cause the error messages by running "pmloadcheck -h hostname1" on hostname2?
You may also want to try killing and restarting any pmloadcheck daemons on hostname2 to see if this will stop the messages.
These messages can be safely ignored, but can potentially indicate that something has not been correctly configured.