After Creating Virtual Doctype in frappe ERPnext I get this Error

ERPNext
,
#1

HI
after following these steps in documentation (Virtual DocTypes) for creating virtual doctype it shows the following error without adding any custom code

AttributeError: 'CustomerSubEntry' object has no attribute '_table_fieldnames'

console log shows this error:


Traceback (most recent call last):

  File "apps/frappe/frappe/app.py", line 69, in application

    response = frappe.api.handle()

  File "apps/frappe/frappe/api.py", line 54, in handle

    return frappe.handler.handle()

  File "apps/frappe/frappe/handler.py", line 45, in handle

    data = execute_cmd(cmd)

  File "apps/frappe/frappe/handler.py", line 83, in execute_cmd

    return frappe.call(method, **frappe.form_dict)

  File "apps/frappe/frappe/__init__.py", line 1581, in call

    return fn(*args, **newargs)

  File "apps/frappe/frappe/desk/form/load.py", line 38, in getdoc

    run_onload(doc)

  File "apps/frappe/frappe/desk/form/load.py", line 369, in run_onload

    doc.set("__onload", frappe._dict())

  File "apps/frappe/frappe/model/base_document.py", line 203, in set

    if not as_value and key in self._table_fieldnames:

AttributeError: 'CustomerSubEntry' object has no attribute '_table_fieldnames'

is there any way to fix this?

thank you soo much in advance