Old process instances not working


Once a new process definition version is deployed, the instances in previous versions are not moving further.
Some are waiting for events. So if I trigger the event, it is processed and goes to next task but after that, it is not moving further and stuck in the subsequent task even if there is no exception.
Some are in error state. If I click retry for the ones in error state, there is no action and delegate is not called.
Is there a way to complete these process instances in previous versions?

Thanks in advance.