Appendix B: Debugging Tips

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Currently, the retail version of Urlmon.dll handles exceptions caused by all pluggable protocols. Developers trying to debug a custom pluggable protocol handler can do one of the following:

• Trap the exceptions in your custom pluggable protocol handler before they get passed to Urlmon.dll.
• Use a debugging tool that has the ability to trap the exceptions before they are passed to Urlmon.dll.

Also, some functions and methods return an HRESULT that is undefined, such as IInternetSecurityManager::SetZoneMapping. Many of these HRESULTs are generated by a macro that sets the low word to a valid Win32® error code and the high word to 8007.