No WCF request is sent from Silverlight on client machine

Question

My SL application is commercial and working just fine on hundreds of machines.

SL is using a WCF service and it works as expected, but today I observed behavior on client machine, where literally no call is made to server.

After you click button that sends a call, some error occures, and no record about WCF call is created in Fiddler.

Error is:

[HttpWebRequest_WebException_RemoteServer]
Arguments: NotFound
Debugging resource strings are unavailable...

I read about this error that people recommend to use Fiddler, but as I say there is no call displayed in Fiddler

So problem is worse than I thought initially.

It comes and goes. Currently we have found a working solution that fixes the problem after it appears although it doesn't make any sense to me.

For example if I get this error in chrome & mozilla & OOB version, launching a program in IE works, and after that chrome,mozilla & OOB start to work too.

Thing is that same people who had this problem solved with this workaround experience it again in some days, like a week, with no apparent reason, and then combination of launches from various locations helps (usually IE helps the most).

Any help appreciated, I start a bounty as its pretty sick bug and I need to fix it somehow.

Update

Weird IE fix scenario:

At some point OOB version gets into state where it doesn't send any WCF request to server. (fiddler doesn't see it, server doesn't gets it). After launching web version in IE, and hitting the same button, that sends WCF request we get desired result in IE web version.

Without changing anything else, just relaunching OOB version which was in this buggest state before, makes OOB version work correctly. Its not reinstalled, not changed - nothing.

This is what I call "IE cure" of this problem. So the question is what can IE launch potentiall change for OOB version?

Answer 1

According to this thread the message Debugging resources are unavailable appears when de client is not using the the Silverlight Developer Runtime.

This means that the actual exception is hidden from you (and us) so the next step is to reproduce the error on a system that has the Silverlight Developer Runtime.

I found this article. It might be worth it to check the certificate you are using (are you using a certificate) It is one of those things that is different with OOB apps and browsers.