Silverlight WSOD at remote client site

I have a client who installed our silverlight app recently. it works fine from their server itself. but when they try to run it from a client, they can log in through the aspx login page, but on the main page, which hosts the tag and the .xap file, they see absolutely nothing!

I cannot see their screens, just get occasional screenshots via email and cross my fingers that they are typing the URL I tell them to. Even Shareview is not working for them - they can see my screen but I cannot see theirs.

So I am pleading - help! Please throw out some wacky ideas. I just learned an hour or so ago that they did not even have silverlight installed, so the mornings debugging effort was a waste of time. So who knows what the next fascinating source of problems is?

Here is the user-agent info. Oor app is .net 4.0 could that be the problem? It does noty look to m开发者_StackOverflow社区y untrained eye that the client supports 4.0 (from the web server log):

Mozilla/4.0+(compatible;+MSIE+7.0;+Windows+NT+5.1;+.NET+CLR+1.1.4322;+.NET+CLR+2.0.50727;+.NET+CLR+3.0.04506.30;+.NET+CLR+3.0.04506.648;+.NET+CLR+3.0.4506.2152;+.NET+CLR+3.5.30729) 401 3 5 0

Getting closer - I see that the GET request for the XAP is returning 401 - not found! What would do that?

It's very possible that they are blocking XAP files either directly or indirectly at the firewall. XAP files are simply ZIP files and inspection-based firewalls tend to look at these as a security risk. You may want to see if they can setup an exception in their rules.

Hmm..

1) check if your client access the good url. Request their IP address, then check the web server logs. ie: are they requesting the good url, are they downloading the xap? (check if they use a proxy, too?)

2) check that they restarted their browser after installing the Silverlight runtime.

3) Do you handle the UnhandledException event for your Application class? If no, use it to send detailed exception logs to your server on application crash.

4) Use javascriptto initialize your Silverlight application. This way, you can be notified if the runtime fail to start, (for example if it failed to load the xap file) You can use ajax to report the issue to the webserver.