Question

Somehow I’ve been lucky and never had to deal with this problem, even though I think it’s a common one:

I’ve got a web project, let’s call it SomeProject. SomeProject has a reference to a 3rd party library, let’s call it SomeThirdParty, version 1.0. SomeProject also has a reference to a home-grown class library, let’s call it SomeLibrary. SomeLibrary also has a reference to SomeThirdParty, but a different version (let’s say 2.0).

Version 1.0 and 2.0 of SomeThirdParty share most of the same signatures, but are different implementations. I need SomeProject to use the 1.0 implementation, and SomeLibrary to use the 2.0 implementation if possible.

I compile SomeProject using its reference to log4net. The DLL that ends up in the bin directory is the one that SomeProject references. At runtime, when code from SomeLibrary runs, it attempts to execute the code from version 2.0 of SomeThirdParty, and of course fails, throwing a FileLoadException: Could not load file or assembly 'SomeThirdParty, Version=2.0.0.0, Culture=[etc.]' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference.

Obviously I could upgrade SomeProject to the newer DLL or downgrade SomeLibrary to the older DLL, but it wouldn’t be ideal for many reasons.

I think the right answer involves installing SomeThirdParty in the GAC, but I’m not sure exactly how I’d go about doing this, and how it would affect other developers and servers.

Any suggestions you may have are appreciated.

Thanks for the help.

Answer 1

Putting both versions of SomeThirdParty into GAC should do what you want. Use gacutil utility or Start->Run->assembly then drag-n-drop.