form.validate_on_submit() error

builtins.TypeError
TypeError: __init__() takes from 1 to 2 positional arguments but 3 were given

Traceback (most recent call last)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1997, in __call__
return self.wsgi_app(environ, start_response)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1985, in wsgi_app
response = self.handle_exception(e)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1540, in handle_exception
reraise(exc_type, exc_value, tb)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1982, in wsgi_app
response = self.full_dispatch_request()
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1614, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1517, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1612, in full_dispatch_request
Open an interactive python shell in this framerv = self.dispatch_request()
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask/app.py", line 1598, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/home/ubuntu/workspace/Inventory/views.py", line 9, in signup
if form.validate_on_submit():
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/flask_wtf/form.py", line 101, in validate_on_submit
return self.is_submitted() and self.validate()
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/wtforms/form.py", line 310, in validate
return super(Form, self).validate(extra)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/wtforms/form.py", line 152, in validate
if not field.validate(self, extra):
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/wtforms/fields/core.py", line 204, in validate
stop_validation = self._run_validation_chain(form, chain)
File "/home/ubuntu/workspace/Inventory/virtualenv/lib/python3.4/site-packages/wtforms/fields/core.py", line 224, in _run_validation_chain
validator(form, self)
TypeError: __init__() takes from 1 to 2 positional arguments but 3 were given
The debugger caught an exception in your WSGI application. You can now look at the traceback which led to the error.
To switch between the interactive traceback and the plaintext one, you can click on the "Traceback" headline. From the text traceback you can also create a paste of it. For code execution mouse-over the frame you want to debug and click on the console icon on the right side.

You can execute arbitrary Python code in the stack frames and there are some extra helpers available for introspection:

dump() shows all variables in the frame
dump(obj) dumps all that's known about the object
Brought to you by DON'T PANIC, your friendly Werkzeug powered traceback interpreter.