ISSUE
When a workflow is started in terminates immediately with the error Another instance of the same workflow with the same ActivationInfo is currently executing. Its instance id is "{workflowInstanceID}"However no running instance on the workflow is shown in the workflow status page.
ERROR CODE
RESOLUTION
Make a note of the "workflowInstanceID" in the error message and Append the below url to the site URL which will get workflow status page. Use "End Workflow" button on this page to stop the workflow instance.
http://{Weburl}/_layouts/15/WrkStat.aspx?List={ListGuid}&WorkflowInstanceName={WorkflowInstanceID} where ListGuid is the ListGUID of the list where issue occurs and workflowinstanceID is the workflow instance ID referenced in the error message.