I was following the instructions on this page Databinding with WPF when I ran into an issue at the Updating code generation for data binding step. I was getting an mscorlib version mismatch error. I could not compile the project.
I had noticed that changing ICollection<T> to ObservableCollection never did the regeneration of the entity code. Running 'Run Custom Tool' on the .tt file also did not work.
After some searching I came across this page mscorlib mismatch when Entity Framework runs transformations. I installed the vs14-kb3151378.exe updated mentioned in the comments section. After the install and reopening my solution in VS 2015, the mscorlib error was gone. The project would successfully compile.
Some posted in the comments about changing the SQL server authentication off of Integrated but I know for many of us that is very much undesirable.
If you run into this issue and have not installed KB3151378, if you are a candidate for the install, I recommend it as it may solve the issue for you too.