SharePoint custom workflow--> InfoPath Edit Task form error --> "This task could not be updated at time time"

 Hi! Experts

   I have a custom state machine workflow with InfoPath Edit task form. Workflow creates a task and sends e-mail notification to approver. Approver gets e-mail and Edit task form popup with correct information when approver clicks e-mail “Edit Task” button.

I get "This task could not be updated at time time" error when approver clicks submit button. Not sure what’s causing this error

Appreciate your help

Thanks

PDesai