The project system has encountered an error When trying to load project : <p>In Visual Studio 2017 v15.7.1 I am getting the following error window when trying to load one of my projects:</p>

<p><a href="https://i.stack.imgur.com/jl3rY.png" rel="noreferrer"><img src="https://i.stack.imgur.com/jl3rY.png" alt="VS error window"></a></p>

<p>And when I go to the path specified, inside the test file I find a very long stack-trace which I could not copy all of it because it exceeds allowed characters count. </p>

<blockquote>
  <p>===================== 5/31/2018 3:40:57 PM LimitedFunctionality System.AggregateException: Project system data flow
  'ProjectBuildSnapshotService Outer 320459' closed because of an
  exception: System.AggregateException: One or more errors occurred.
  ---> System.AggregateException: One or more errors occurred. ---> System.AggregateException: One or more errors occurred. --->
  System.AggregateException: One or more errors occurred. --->
  System.NullReferenceException: Object reference not set to an instance
  of an object.    at
  Microsoft.VisualStudio.ProjectServices.DesignTimeBuilder.d__17.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.ProjectSystem.Build.DesignTimeBuilderService.BuilderLifetimeHelper.d__12.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.ProjectSystem.Build.DesignTimeBuilderService.d__36.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  Microsoft.VisualStudio.ProjectSystem.Build.DesignTimeBuilderService.d__36.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)<br>
  at
  Microsoft.VisualStudio.ProjectSystem.Build.DesignTimeBuildManagerService.d__55.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)<br>
  at
  Microsoft.VisualStudio.ProjectSystem.Build.DesignTimeBuildManagerService.d__53.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.ProjectSystem.Designers.ProjectBuildSnapshotService.d__74.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)<br>
  at
  Microsoft.VisualStudio.ProjectSystem.Designers.ProjectBuildSnapshotService.&lt;>c__DisplayClass72_0.&lt;b__0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.Threading.JoinableTask.d__78.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.Threading.JoinableTask<code>1.&lt;JoinAsync&gt;d__3.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.ProjectSystem.Designers.ProjectBuildSnapshotService.&lt;UpdateSnapshotCoreAsync&gt;d__72.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)<br>
  at
  Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase</code>3.d__34.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase<code>3.&lt;&gt;c__DisplayClass32_0.&lt;&lt;Initialize&gt;b__1&gt;d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.Threading.JoinableTask.&lt;JoinAsync&gt;d__78.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase</code>3.&lt;b__32_0>d.MoveNext()
  --- End of stack trace from previous location where exception was thrown ---    at
  System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task
  task)    at
  System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task
  task)    at
  Microsoft.VisualStudio.ProjectSystem.DataflowExtensions.&lt;>c__DisplayClass24_0`2.&lt;b__0>d.MoveNext()</p>
</blockquote>
