tim.wentzell

I was lucky (sort of) – I contacted my client and it just so happens that they’ve recently decided to discontinue their business with InboundWriter.

So – problem solved – plugin disabled => WP 3.9 upgrade completed.

Sorry – and I know it is the InboundWriter plugin that is at fault by process of elimination (disabling 1 plugin at a time and testing the post text tab switching each time).

By keeping all of my original plugins active and disabling just the InboundWriter the post text tab switching is restored.