Edit event dates displays error in dashboard but no info is provided

**To Reproduce**
After updating a pre-existig event with new dates, the following message appears in the dashboard but no indication of what the error is about is shown.

**Expected behavior**
If some data validation shows issues, I'd expect to be displayed in the dashboard of the general event view.

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Desktop (please complete the following information):**
- OS: Linux
- Browser: Firefox
- Version: 2.0-M2-SNAPSHOT

**Additional context**
Basically, we want to update a past cancelled event (for COVID) with metadata for new event, keeping all sold tickets and other information for the current new. So far, other than this issue, the only other problem is we cannot update the url, but I think we can live with it.