Failed to find the RegisterModule entrypoint in the module DLL… - what's going on?

Question

I have an ISAPI module (native - NO ASP.net etc) written in Delphi XE. Trying to run it on IIS 7.5 on a Win 7 64 enterprise desktop machine.

App pool, webSite, etc are configured correctly, ISAPI module is permissioned to execute, classic pipeline, 32 bit etc - have performed these operations many times.

Same module runs fine on a Win 2008 R2 server and it USED to run on my Win 7 desktop IIS 7.5 as well.

But my hard drive died last week and I got a new Win 7 installation - the standard corporate wide Win 7 Enterprise image (not the same as my previous Win 7 64 installation).

Now when launching the module, browser hangs a bit and then returns "HTTP Error 503. The service is unavailable." In IIS, I see that my app pool is stopped after the error occurs - which I know means a serious error occurred in the web application.

In the windows event log I found this message:

"Failed to find the RegisterModule entrypoint in the module DLL G:\Mikey.dll. The data is the error."

Some debug strings showed me the error surfaces after application.run is called in the DLL dpr.

What's going on here? How can I fix this? I need this deployment for my development work.

Please - the dll is properly permissioned to execute code and the app pool is properly configured - a good deal of my initialization code executes in the DLL BEFORE application.run is called - so this is not a simple configuration or permissions issue - the 503 error and the event log entry also indicate such.

Answer 1

I found the clue to my problem @

http://forums.iis.net/p/1162012/1921878.aspx

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Re: Messed-up site configuration; "Failed to find the RegisterModule ..." error in Event Log 10-22-2009, 8:48 PM Remove aspnet_isapi.dll from your modules list - it is an ISAPI extension, not a module. Anil Ruia Senior Software Design Engineer IIS Core Server

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Realized that when initially I installed IIS, I did not see the CGI/ISAPI restrictions applet and permissioned my dll in a different fashion.

Later I found that I had to install the ISAPI support specifically - when I did that I permissioned my DLL again, the right way, and deleted the original module entry (or so I thought).

This page tipped me off - my dll was probably registered/permissioned incorrectly and IIS was running it as module, not an extension - thus: " "Failed to find the RegisterModule".

Since this is brand new deployment, I simply uninstalled all IIS modules and features, made sure there were no old config files left around and scrubbed down the registry.

Then I reinstalled IIS with the ISAPI restriction feature included and registered/permissioned my ISAPI module as required and set up the app pool and web site. Now all is well.

Thank you Anil Ruia (wherever you are...)

Answer 2

I was getting this error with a Perl module. I had to disable it from applicationHost.config. I found out that if you just edit %Windir%\system32\inetsrv\config\applicationHost.config with an editor, the changes aren't reflected on IIS, even though the file gets written correctly, even if you restart IIS. The only way to do it is following this guide https://technet.microsoft.com/en-us/library/cc735153(v=ws.10).aspx. You basically need to launch "Notepad" from en elevated command prompt to edit applicationHost.config. That's how I solved this problem.