AttributeError: 'NoneType' object has no attribute '_table' on deleting a custom field

sneha antony

I created certain custom fields to be added in Sales/Contracts.When I tried to remove some fields among those it shows the following error.

Client Traceback (most recent call last): File "/opt/openerp/server/openerp/addons/web/", line 204, in dispatch response["result"] = method(self, *self.params) File "/opt/openerp/server/openerp/addons/web/controllers/", line 1125, in call_kw return self._call_kw(req, model, method, args, kwargs) File "/opt/openerp/server/openerp/addons/web/controllers/", line 1117, in _call_kw return getattr(req.session.model(model), method)(args, **kwargs) File "/opt/openerp/server/openerp/addons/web/", line 42, in proxy result = self.proxy.execute_kw(self.session._db, self.session._uid, self.session._password, self.model, method, args, kw) File "/opt/openerp/server/openerp/addons/web/", line 30, in proxy_method result = self.session.send(self.service_name, method, *args) File "/opt/openerp/server/openerp/addons/web/", line 103, in send raise xmlrpclib.Fault(, formatted_info)

Server Traceback (most recent call last): File "/opt/openerp/server/openerp/addons/web/", line 89, in send return openerp.netsvc.dispatch_rpc(service_name, method, args) File "/opt/openerp/server/openerp/", line 292, in dispatch_rpc result = ExportService.getService(service_name).dispatch(method, params) File "/opt/openerp/server/openerp/service/", line 626, in dispatch res = fn(db, uid, params) File "/opt/openerp/server/openerp/osv/", line 190, in execute_kw return self.execute(db, uid, obj, method, *args, *kw or {}) File "/opt/openerp/server/openerp/osv/", line 132, in wrapper return f(self, dbname, args, *kwargs) File "/opt/openerp/server/openerp/osv/", line 199, in execute res = self.execute_cr(cr, uid, obj, method, args, *kw) File "/opt/openerp/server/openerp/osv/", line 187, in execute_cr return getattr(object, method)(cr, uid, args, *kw) File "/opt/openerp/server/openerp/addons/base/ir/", line 324, in unlink self._drop_column(cr, user, ids, context) File "/opt/openerp/server/openerp/addons/base/ir/", line 306, in _drop_column cr.execute('select relkind from pg_class where relname=%s', (model._table,)) AttributeError: 'NoneType' object has no attribute '_table'.

What are the possible reasons and solutions for this issue?