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Editorial Team
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Asked: 2026-06-01T04:25:46+00:00

I am getting an exception on my server side code, which is serving up

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I am getting an exception on my server side code, which is serving up a silverlight app,

Win32Exception – No such interface supported

Our server side C# code starts up a separate process for a short task because of a third party dll not being thread safe. So the error above occurs in part of the code like this,

Process process = new Process();

ProcessStartInfo processStartInfo = new ProcessStartInfo();

processStartInfo.CreateNoWindow = true;
processStartInfo.WindowStyle = ProcessWindowStyle.Hidden;

processStartInfo.FileName = 
    Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "bin", "PreviewGenerator.exe");

process.StartInfo = processStartInfo;

process.Start(); // THIS IS WHERE THE EXCEPTION OCCURS
process.WaitForExit();

The PreviewGenerator.exe process does not start when it is not working, the exception occurs where the comment is above.

UPDATE:

I have run process monitor on the IIS server when the issue occurs. This shows that the w3wp process does this,

Thread Create
Access the file PreviewGenerator.exe
Hive unloaded (this is the registry)
Thread Exit

And it does this before calling the other process. If I compare this with a the process monitor log when it is working it does this,

Thread Create
Access the file PreviewGenerator.exe
Process Start
Does heaps of stuff with PreviewGenerator.exe including reading / writing / registry, etc.
Process Exit
Hive unloaded
Thread Exit

But process monitor does not show any information as to why the first case doesn’t work.

Is there a way I can see why the thread exits prematurely?

Also I think this problem relates to when my server is being loaded up more, and much more memory is being used. How can I prove this?

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1 Answer

  1. Editorial Team

    I found the best thing to do was to create a separate app pool for my application in IIS and set an upper limit for the amount of RAM it could use. Also I found it useful to turn on the ‘Generate Recycle Event Log Entry’ items under the app pool settings.

    You can then go to the system event log and filter out the items with a source of ‘WAS’ to understand what is going on in the app pools, when they are restarting and when they stop from being idle etc.

    I think the main problem in our case is that the IIS box was running out of memory. Tuning the app pools and adding some extra RAM seems to have solved it.

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