Visual Studio refuses to build project due to missing assembly reference that isn't missing

In my case, target Framework of Assembly Project and the target Framework of the project where i want to use this assembly are different. Target framework of assembly project was 4.5 and target framework of my project was 4.0.

When I have change the target framework of my project to the target framework of assembly project i.e. from 4.0 to 4.5 , it works fine.

For change the Target Framework of project,

Right Click the project -> Properties -> Application -> Target Framework

This Target Framework is drop-down list, select your required Framework from this list.

1.remove all references

2.Build --> Clean solution

3.Clean your project using this project as sometimes visual studio fails to clean everything neatly.

Another possible issue could be mismatch in targeted versions of .NET between the assemblies. I experienced the same symptoms and setting the same version of framework did the trick for me.