wagtail/docs/editor_manual/new_pages/required_fields.rst

Required fields
~~~~~~~~~~~~~~~

* Fields marked with an asterisk are required. You will not be able to save a draft or submit the page for moderation without these fields being completed.

..  image:: ../../_static/images/screen22_required_field.png

* If you try to save/submit the page with some required fields not filled out, you will see the error displayed here.
* The number of validation errors for each of the *Promote* and *Content* tabs will appear in a red circle, and the text, 'This field is required', will appear below each field that must be completed.

..  image:: ../../_static/images/screen23_validation_error.png