FRM-40200. Field is protected against update.
User is trying to change one of accounts to read only. When he changes the roles an error 'FRM-40200 Field is protected against update' appears, even though the admin account is used.
In this form, you can’t update the entry. Please delete roles that you would like to change and add new ones.
Note the HIG_USER is internal role ant it must be assigned to the user.