I am not sure to raise this with Nintex support or not? I thought initially that this was a SharePoint error as the error was pointing to a Web part as below
But looking into the SharePoint Logs for the Correlation ID, I noted that this is actually a Nintex Workflow error -
Failed to retrieve form from workflow. Error: Cannot find the task form. Please check the action's form in the Workflow Designer..
Just to confirm that the prior to this all the workflows that are in progess work correctly and we can edit the task
The only thing that has changed on the workflow is the approver and it was republished.
Does anyone have any ideas or should I raise this with Support?