I have a SharePoint 2013 PWA with Nintex Workflow for Project server.
For one of a project, Demand Management Workflow is throwed error and Submit button is grayed out. Please refer the scree shot.


I tried to change the workflow and restart the workflow. but I am getting following error.
- Error:
- WorkflowCannotChangeWorkflow (35109). Details: id='35109' name='WorkflowCannotChangeWorkflow' uid='46558a53-e4a7-e911-942e-005056bc72cc'.
- Queue:
- GeneralQueueJobFailed (26000) - WorkflowChangeWorkflow.WorkflowChangeWorkflowMessage. Details: id='26000' name='GeneralQueueJobFailed' uid='47558a53-e4a7-e911-942e-005056bc72cc' JobUID='35fb2253-e4a7-e911-942e-005056bc72cc' ComputerName='c4be40d5-e127-46ea-b716-c992cf884d39' GroupType='WorkflowChangeWorkflow' MessageType='WorkflowChangeWorkflowMessage' MessageId='1' Stage='' CorrelationUID='a2dbf09e-2195-b0af-84d3-9d70e596ae02'. For more details, check the ULS logs on machine c4be40d5-e127-46ea-b716-c992cf884d39 for entries with JobUID 35fb2253-e4a7-e911-942e-005056bc72cc.
Same demand workflow is working for other projects. But failed for this.
Can someone guide me how to resolve this isssue.