ALERT: Give a message to the User when a field needs to be entered/corrected/edited to save/submit it

When you enter an event or go to edit an event, if you skip a field (most often the Event Type), and try to submit or save the screen, it will not do anything because data is missing. The problem we are seeing with this is that since there is no error message that pops up, the user is not redirected to the field needing to be corrected and nothing is highlighted, users are struggling because they don't know what's wrong.