Web Client : cannot marshal None unless allow_none is enabled

Hello,

With web client getting ERROR.

Web Client : cannot marshal None unless allow_none is enabled

OpenERP WebClient Error
Client Traceback (most recent call last):
  File "/home/tiny/sources/client-web/openerp-web/addons/web/common/http.py", line 176, in dispatch
    response["result"] = method(controller, self, **self.params)
  File "/home/tiny/sources/client-web/openerp-web/addons/web/controllers/main.py", line 839, in call
    return self.call_common(req, model, method, args, domain_id, context_id)
  File "/home/tiny/sources/client-web/openerp-web/addons/web/controllers/main.py", line 835, in call_common
    return getattr(req.session.model(model), method)(*args)
  File "/home/tiny/sources/client-web/openerp-web/addons/web/common/openerplib/main.py", line 430, in proxy
    *args)
  File "/home/tiny/sources/client-web/openerp-web/addons/web/common/openerplib/main.py", line 306, in proxy
    result = self.connector.send(self.service_name, method, *args)
  File "/home/tiny/sources/client-web/openerp-web/addons/web/common/openerplib/main.py", line 130, in send
    return getattr(service, method)(*args)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1483, in __request
    allow_none=self.__allow_none)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1132, in dumps
    data = m.dumps(params)
  File "/usr/lib/python2.6/xmlrpclib.py", line 677, in dumps
    dump(v, write)
  File "/usr/lib/python2.6/xmlrpclib.py", line 699, in __dump
    f(self, value, write)
  File "/usr/lib/python2.6/xmlrpclib.py", line 759, in dump_array
    dump(v, write)
  File "/usr/lib/python2.6/xmlrpclib.py", line 699, in __dump
    f(self, value, write)
  File "/usr/lib/python2.6/xmlrpclib.py", line 703, in dump_nil
    raise TypeError, "cannot marshal None unless allow_none is enabled"
TypeError: cannot marshal None unless allow_none is enabled

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See attached screenshot.

Thanks,
Tejas - TTA