I get the following error on an MSBuild: MSB3107
C:\Windows\Microsoft.NET\Framework64\v3.5\Microsoft.Common.targets (1001): The specified project reference metadata for the reference "....\Contracts\Contracts.csproj" is missing or has an invalid value: Project
Since I didn't found many information on the internet on MSB3107 I'll figured I'll post it here.
I solved this, by removing all the references to Contracts.csproj and put them back with program reference. This was an easy fix.