I am getting the following error when I deploy a page layout containing the related list of open activities.
Invalid field:TASK.SUBJECT in related list:RelatedActivityList
Now to get the deployment to pass, I needed to remove the XML part of the page layout that contains details for this related list. Why is this happening, isn't this a reference to a standard field? Any thoughts guys.
<enableActivities>true</enableActivities>
but like the answer from George S suggests, I had to toggle this false (push) then true again (push) before my layout would push