Error message

"diameter process ingress error Improper version"

I got this error either, and have opened case to F5 support.

Here is conclusion of the answer :

It is related to the ingress packet checking and it seems that a Diameter device has set a bad version number in the Diameter header. Based on RFC 3588, the version number should be set to '1'. The log message should be harmless.

To assist in checking what is the version number set and the servers involved, you may wish to implement the following iRule to log the respective packets to the log files:

when DIAMETER_INGRESS {
   if { not ([DIAMETER::header version] == "1") } { 
      log local0. "Diameter origin [DIAMETER::host origin] from [IP::remote_addr] sent probable bad version [DIAMETER::header version]" 
    } else {
      log local0. "Diameter version OK: [DIAMETER::header version]"
   } 
}