You need to change the Permalink settings via WordPress core.
Settings -> Permalinks
Click the “Post name” radio button, then click the “Save Changes” button
Looks like this is what you need…
/(\d*)/(\d*)/([A-Za-z0-9-]*).html
/category/$3
Live RegEx link: http://www.phpliveregex.com/p/lrv
I just updated to 2.8.2 and confirm the issue is no longer.
When editing an event, I don’t need to change anything. I click the Update button, and the warnings show.
If I edit one of the dates then update, the warnings show
If I edit both dates then update, the warnings show.
