Hé Kilian, thanks for the advice.
About adding that guid ourselves, if you say add that to the message, do I understand it correctly that we should do this :
AllExceptions.ExceptionMessage = AllExceptions.ExceptionMessage + " (code : " + GenerateGuid() + ")"
Does that modification to the ExceptionMessage we apply on OnException get persisted in the error record visible in service center?
edit : no wait, that does not make any sense :-) perhaps you mean the client action LogMessage? In that case I do understand it and it would indeed be searchable in service center, but that message is not really an Error, right? Is there a LogError action available to achieve this?