We are using OpenEdge 11.7.4 on PASOE servers, and on the OE .Net openclients.  The openclients connect to PASOE via the APSV transport.

It is rare but once in a while the entire appdomain which is used to make these openclient connections will become "corrupted", for lack of a better word.  And all state-reset (aka. session-managed) openclient requests will fail until the appdomain is restarted.  This is especially bothersome considering the fact that these app-objects and proc-objects are supposed to be independent of each other (they are new'ed up from scratch whenever we make a round-trip to PASOE.)

The exception that is thrown is very unhelpful (as is the case with many exceptions from the .Net openclient).  It suppresses the full callstack and it obscures the true underlying exception - since it doesn't attach it as an "Inner" exception.  Here is the message that we get for the entire lifetime of the appdomain, until it is restarted.:

Progress.Open4GL.DynamicAPI.SessionPool+NoAvailableSessionsException: SessionPool : NoAvailableSessions[CONNECT FAILURE: Unable to resolve hostname grpoeprod (8821) ]

Of course if we go to the server and attempt to ping the hostname "grpoeprod" there is no problem resolving that name.  Similarly if we launch other client applications, they have no problems.  And finally, if we cycle the appdomain which had become "corrupted", then it won't have problems again after it restarts.

I'm pretty sure this is similar to an issue I had reported in the past : PSC00355194.  That was back in the days when we were connecting our .Net openclient to "classic" appserver on HP-UX.  At the time I was fairly convinced that the problem was related to certain static members in .Net that had no concurrency protection.  Supposedly the related bug was going to be fixed in an early SP on 11.7 (11.7.1 I believe).  But we are up to SP 11.7.4 now, and we are still having these rare problems.

It would probably take a day or two to come up with a repro for this and submit it.  Is there still work being done to fix the .net openclient in 11.7?  I know the 11.7.5 SP was released, and I have to admit that this is a rare issue.  But it is a very disruptive issue, however, and involves recognizing the bug from the error messages, and stopping and restarting the appdomain that is failing.  In some cases it is a mission-critical appdomain used in a Windows Service.  

Has anyone else experienced this bogus error in the .net openclient: "Unable to resolve hostname"

The KB articles don't make reference to the bogus variety of the error; the only KB's I've found are the instances where the error message was legitimate.