There have been some instances where the above update renders the owa virtual directories inoperable. After much trawling about I discovered that the rollup doesn't update the owa directories too make them compatible. To do this open up Windows Power Shell and type the following command:

updateowa.ps1

This should update the directories and make them workable again.

Ignore the MS advice of deleting and re-creating the owa virtual directories unless this does not work.