Error while loading 'Core' module

In beta.erpnext, when I search for ‘Core’ in awesome bar and click on ‘Core Module’ , I get the following error:

Traceback (most recent call last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/desk/form/”, line 37, in getdoc
raise frappe.PermissionError, (“read”, doctype, name)
PermissionError: (u’read’, u’DocType’, u’Custom DocPerm’)

In my local installation, I get the following:
Traceback (most recent call last):
File “/home/ubuntu/frappe-bench/apps/frappe/frappe/”, line 55, in application
response = frappe.handler.handle()
File “/home/ubuntu/frappe-bench/apps/frappe/frappe/”, line 21, in handle
data = execute_cmd(cmd)
File “/home/ubuntu/frappe-bench/apps/frappe/frappe/”, line 53, in execute_cmd
return, **frappe.form_dict)
File “/home/ubuntu/frappe-bench/apps/frappe/frappe/”, line 907, in call
return fn(*args, **newargs)
TypeError: get() takes exactly 1 argument (0 given)

Appreciate any help. Thanks.