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asp.netdlliis-6unmanaged

Unmanaged DLLs fail to load on ASP.NET server

This question relates to an ASP.NET website, originally developed in VS 2005 and now in VS 2008.

This website uses two unmanaged external DLLs which are not .NET and I do not have the source code to compile them and have to use them as is.

This website runs fine from within Visual Studio, locating and accessing these external DLLs correctly. However, when the website is published on a webserver (runnning IIS6 and ASP.NET 2.0) rather than the development PC it cannot locate and access these external DLLs, and I get the following error:

Unable to load DLL 'XYZ.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

The external DLLs are located in the bin directory of the website, along with the managed DLLs that wrap them and all the other DLLs for the website.

Searching this problem reveals that many other people seem to have the same problem accessing external non.NET DLLs from ASP.NET websites, but I haven't found a solution that works.

I have tried the following:

  • Running DEPENDS to check the dependencies to establish that the first three are in System32 directory in the path, the last is in the .NET 2 framework.
  • I put the two DLLs and their dependencies in System32 and rebooted the server, but website still couldn't load these external DLLs.
  • Gave full rights to ASPNET, IIS_WPG and IUSR (for that server) to the website bin directory and rebooted, but website still couldn't load these external DLLs.
  • Added the external DLLs as existing items to the projects and set their "Copy to Output" property to "Copy Always", and website still can't find the DLLs.
  • Also set their "Build Action" property to "Embedded resource" and website still can't find the DLLs.

Any assistance with this problem would be greatly appreciated!

Solution

  • Try putting the dlls in the \System32\Inetsrv directory. This is the working directory for IIS on Windows Server.

    If this doesn't work try putting the dlls in the System32 directory and the dependency files in the Inetsrv directory.