Receiving TF214015 in TFS 2013

Hello everyone,

I have a pre-production TFS 2013 server which has worked great until this past weekend.  We had Octopus deploy running on the same machine, and after it was deprecated in our build/deployment process we decided to remove it.  After doing so and restarting the machine, we began seeing the following error in our event logs:

Exception Message: TF214015: The build client object model does not support Team Foundation Server 2005 or Team Foundation Server 2008. (type NotSupportedException)
Exception Stack Trace:    at Microsoft.TeamFoundation.Build.Hosting.BuildMachine.StartOperation.End(IAsyncResult result, HttpRouter& router, TfsMessageQueue& messageQueue, List`1& processHosts, MachineLifecycleActivity& traceActivity)
   at Microsoft.TeamFoundation.Build.Hosting.BuildMachine.EndStart(IAsyncResult result)
   at Microsoft.TeamFoundation.Build.Machine.WindowsService.EndStartMachine(IAsyncResult result)

The TFS application tier works just fine as far as I can tell, but the TFS Build service will not start.  I uninstalled TFS and re-installed the App Tier and Build service and restarted the machine numerous times during the process but that didn't fix anything.

At this point the only thing I haven't checked is the TFS config database, but I'm unsure how to do that or what to look for.

This comes at a (really) bad time for us as we're evaluating whether we should go with Atlassian Stack or TFS!  ;)

I suppose something really bad happened when we removed Octopus deploy.

Any help or pointers would be greatly appreciated!