There's virtually no BizTalk-related error that's more frustrating than exposing an orchestration as a web service, trying to call it, and getting the horrific "Internal Server Error" or "Internal SOAP Processing Failure". To make it even more fun, you'll frequently find absolutely nothing in the event log. 9 times out of 10, this is related to security, permissions and Application Pool.

Now that you're thoroughly depressed, let me at least point out my standard mode for trying to diagnose and fix this. First of all, this knowledge base article is a great place to start with. It covers common symptoms and fixes for various web service related issues you'll come across. Some of the other steps I usually follow include:

• Flip on the ThrowDetailedError flag in your web.config file.
• Make sure that the Application Pool user account is a member of both the domain "BTS Isolated Host Users" group, AND, the local IIS_WPG group. That user needs the appropriate rights to the BizTalk MgmtDb which the Isolated group has.
• That same user needs full control to the c:\windows\temp directory on the server.
• Reset IIS after making app pool changes, and when all else fails, reboot.
• Get desperate and make the app pool account a local and/or domain administrator. I never recommend this unless you're trying to firmly isolate the problem as being permissions-based, and not something else.

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