onBeforeSaveUser validation for existing user but not new user
If you hit the submit button and don't fill out any fields. Then the only errors back are Email and Password (standard and set out by Craft). If you do enter an email and password then my validation code works and it errors again this time with the firstName and lastName errors. But these don't trigger on first submit when all fields are blank.


This is a known issue (specifically with the UserModel when saving a user) because "First Name" and "Last Name" aren't true fields in Craft, but more special case fields.

When saving a user, the UserModel validation runs first and immediately bails when the validation error occurs before the onBeforeSaveUser event fires not giving any plugins a chance to participate.

This will be fixed in the upcoming Craft 3 release.