Unable to uninstall the assembly from GAC.

Question

I have encountered an issue while upgrading an application from .Net Framework 3.5 to latest version with .NET Framework 4.5.1. I came into a situation, where one application is using a logger assembly built with .NET framework 3.5, another application(built on 4.5.1) tries to uninstall same logger assembly which is being used by previous application, but it couldn’t proceed. As it keeps on searching the logger assembly in 4.0 GAC and takes significantly lot more time.

However above scenario works smoothly where older and newer applications are built on .NET Framework 3.5 only.

Note: Assembly is getting uninstalled by windows installer not by GACUTIL utility.