Hello!
The issue in here is that, change_email is a required script to update email address or its verification status. Here is documentation about the change_email script.
This is not possible to be performed via the Dashboard.
To update the change_email script, you can do it via our Management API or the Auth0 Deploy CLI tool.
Note that if you change any aspect of a connection via the Dashboard in Auth0, and that connection makes use of a Change Email script, then the script will be deleted.
Thank you!