SP 2013 VS Workflow error “MTW Client is invalid”

When deploying a Workflow enabled app from Visual Studio (2012/2013), receive the error "MTW Client is invalid". More of the same error in the ULS logs.

SharePoint 2013 designer Workflows deploy and run successfully.

Additionally, found these errors in the ULS logs when deploying the Visual Studio workflow:

Microsoft.Workflow.Client.ScopeNotFoundException: Scope '/SharePoint/default/4b83fcb9-1856-4c09-a710-f200fbbebdb7/d2ca60f6-1118-41de-8585-c913de1628ec' was not found.  HTTP headers received from the server - ActivityId: c85e6f54-2b1a-40ea-9a47-5bd949c27bd4. NodeId: D1S2008R2WF1. Scope: /SharePoint/default/4b83fcb9-1856-4c09-a710-f200fbbebdb7/d2ca60f6-1118-41de-8585-c913de1628ec. Client ActivityId : 34d7efbe-e6f3-4c83-bd32-26d331eec32f. ---> System.Net.WebException: The remote server returned an error: (404) Not Found.
 at Microsoft.Workflow.Common.AsyncResult.End[TAsyncResult](IAsyncResult result)
 at Microsoft.Workflow.Client.HttpGetResponseAsyncResult`1.End(IAsyncResult result)
 at Microsoft.Workflow.Client.ClientHelpers.SendRequest[T](HttpWebRequest request, T content)
-- End of inner exception stack trace ---
 at Microsoft.Workflow.Client.ClientHelpers.SendRequest[T](HttpWebRequest request, T content)
 at Microsoft.Workflow.Client.WorkflowManagementClient.SendRequest[T](HttpWebRequest request, T content)
 at Microsoft.Workflow.Client.ScopeManager.Get()
 at Microsoft.SharePoint.WorkflowServices.ExternalSubscription.DeleteServiceGroup(String scopeAddress, String name, ICredentials credentials, Boolean isER, Boolean force) StackTrace:  at Microsoft.Office.Server.Native.dll: (sig=b9944ebb-0ede-47fe-ba7c-79e940e3c2c5|2|microsoft.office.server.native.pdb, offset=131CE) at Microsoft.Office.Server.Native.dll: (offset=21BFD)  34d7efbe-e6f3-4c83-bd32-26d331eec32f

System.InvalidOperationException: MTW client is invalid
 at Microsoft.SharePoint.WorkflowServices.DGWorkflowDeploymentProvider.ValidateClient()
 at Microsoft.SharePoint.WorkflowServices.DGWorkflowDeploymentProvider.Deploy(WorkflowScopeIdentifier scopeId, SPWorkflowPart parts, Dictionary`2 listIdDictionary)
StackTrace:  at Microsoft.Office.Server.Native.dll: (sig=b9944ebb-0ede-47fe-ba7c-79e940e3c2c5|2|microsoft.office.server.native.pdb, offset=131CE)
 at Microsoft.Office.Server.Native.dll: (offset=21BFD)  34d7efbe-e6f3-4c83-bd32-26d331eec32f

Please help!