II7: ISAPI Wildcard Extension generates 500 error (0x8007007f)

Question

I've written an ISAPI extension using Visual Studio 2012 on windows 7 that is a very simple passthrough wildcard extension. When compiled as 32 bit, and with the app pool set to allow 32 bit applications the filter works well. But when I compile as 64 bit (and change the pool to NOT allow 32 bit) I get a 500 error with the code 0x8007007f. 64 bit depends shows all green. There are no errors in the event log. I tried moving the DLL to C:\\Windows\\System32 but am getting the same error. Any help would be greatly appreciated.

Thanks

Marc

Answer 1

The reason might have been that the 64 bit DLL did not export the functions HttpExtensionProc and GetExtensionVersion, which the error name hints at:

Logfile:
Notification
EXECUTE_REQUEST_HANDLER 
ErrorCode
The specified procedure could not be found.
 (0x8007007f) 

I had missed adding the .def file to the linker options in my project.