ERPNEXT new field bug

I can’t create any create any new field under doctype while i updated my erpnext and frappe. my erpnext version is ERPNext: v6.20.0 and frappe version is Frappe Framework: v6.21.0. While I am tring to create new field it’s don’d show level. And I fatch another problem too. While I am tring to get a existing child field from js file I don’t while the field type is int. but if the field type is different from int then I can.
Please give me a solution.