Error saving default text in Dex

Plone Support
1

Plone 5.1

===========================
Actions:

  1. in Dex, clone Event
  2. add field (text)
  3. enter text into box
  4. press 'save default' get this error:
    =============

Traceback (innermost last):
Module ZPublisher.Publish, line 138, in publish
Module ZPublisher.mapply, line 77, in mapply
Module ZPublisher.Publish, line 48, in call_object
Module plone.z3cform.layout, line 63, in call
Module plone.z3cform.layout, line 47, in update
Module plone.z3cform.fieldsets.extensible, line 65, in update
Module plone.z3cform.patch, line 30, in GroupForm_update
Module z3c.form.group, line 145, in update
Module plone.app.z3cform.csrf, line 22, in execute
Module z3c.form.action, line 98, in execute
Module z3c.form.button, line 315, in call
Module z3c.form.button, line 170, in call
Module plone.schemaeditor.browser.schema.listing, line 118, in handleSaveDefaults
Module zope.interface.interface, line 422, in getDescriptionFor
KeyError: 'IRelatedItems.relatedItems'

Ideas?

2

it's a bug

3

I tested further and found the issue is with the "behaviors" if I remove all of them it works fine.

added bug : https://github.com/plone/plone.app.dexterity/issues/270