Unable to See New Method on GAC’d Assembly

A team member and I were having a heck of a time a couple of weeks back as we tried to make use of a new method added to a POCO class that Ravi created.

For what appeared to be no reason (at the time), the newly created method was unavailable to external classes and assemblies.  The code looked something like this:

public class StringOperations
public static string NewOperation(string str)
return string.IsNullOrWhiteSpace(str) ? null : str;
...other operations

Nothing out of the ordinary here.  It’s a pretty simple function–just returns a null if you pass in a null or white-space string, otherwise the string itself.  However when this was referenced either by project reference or by referencing the assembly directly, it wasn’t available through intellisense and any attempt to build with a call to the function resulted in failure.

As we were scratching our heads, we tried a number of things you typically do when Visual Studio doesn’t allow you to build code with an external method call, such as:

  • Rebuild all the projects
  • Clean/Rebuild
  • Un-Reference/Re-Reference
  • Restart Visual Studio
  • Reboot the machine
  • …etc

The assembly had been deployed to the GAC previously, so we wanted to see if that played a role in our troubles.  As it turned out, it did.

When an assembly is in the GAC its definition, for better or worse, is contained there as well and it appears that, regardless of how we’re referencing it, Visual Studio likes to use that version.  So in our next attempt we wanted to remove the assembly from the GAC using gacutil like so:

gacutil /u [AssemblyName].dll

Unfortunately, this did not work either.  The next thing we tried was to un-GAC the assembly by manually deleting it from the cache.  This had worked for me in the past, but it failed here as well.

My colleague then tried using gacutil in a different way.  This time, giving a fully-qualified assembly reference, like so:

gacutil /u "[ourAssemblyName], Version=, Culture=neutral, PublicKeyToken=[thePublicKey]"

Bingo!  That did it.  Perhaps through the build/re-build and gac/re-gac process of our development, we confused Visual Studio or .NET on our machines.  I have no idea.  But one more thing to try if you hit the gac/re-gac stage is to use the fully-qualified overload of gacutil /u.

Good luck!  I hope it helps!


About Ed Jones

Ed is a .NET and Integration architect for Avanade in the Twin Cities. Contact Ed

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