isapi dll running on IIS6 gives "The specified module could not be found" error, why ?
Posted on 2011-02-28
OK, I know, as soon as you see something like this when trying to run a isapi.dll in IIS you probably say ... it's not configured properly or permissions.
Well me too, but I'm horribly perplexed by this one ...
I have two different Delphi/IntraWeb isapi.dll in the SAME virtual directory. One works just fine, the other gives "The specified module could not be found". Each dll has the same properties in IIS and each has the same properties/permissions at file level in NTFS. Also ...
1. Both dlls require access to MySQL server, the workng one achieves this correctly, so I currently don't think it is a reference to any MySQL extension.
2. Being IIS6, I definitely have setup the errant isapi.dll (as well as the working one) as an allowed web extension and changed this as I've moved it between virtual directories during attempts to get it to work.
3. Just for testing, I have given all groups full control permissions at file level. Even that didn't help.
4. The non-working dll requires registry access (specifically coded as read only to HKEY_LOCAL_MACHINE ... I think this is allowed) to get some initial settings information. Perhaps this would cause the problem ? ... if so, what is required by way of permissions/configuration within IIS to allow the dll to read the registry ? However I have tried recompiling the dll with no requirement to read the registry and still have the same problem.
5. Looking at the associated IIS website logfile, I see that with the dll which runs OK I am getting sessions and what appear to be 200 OK responses but with the non-working dll I get 500 responses with no sessions started (if I'm interpreting the logfile correctly)
It seems that I need, for some reason, a different configuration for the non-working dll. I'm really stuck with this, what exactly is IIS6 trying to tell me ? ... I'm not the greatest with IIS, how could I find out which module it is referring to and fix this ?
thanks and best regards