when use email template to send mail, there is error in ubuntu but no in windows 7 (development)

source code as following

 res = super(kanban_OrderTracking, self).create(vals)

if not is_production_order_available and res.workstation.planners.ids:
            obj_email_template = self.env['email.template']
            email_template = obj_email_template.search([('name', '=', 'no order for new kanban')], limit=1)
            if email_template:
                partner_to = reduce(lambda x, y: str(x) + ',' + str(y), res.workstation.planners.ids)
                email_template.write({'partner_to': partner_to})
                self.env.invalidate_all()
                email_template.send_mail(res.id, force_send=True)

server logs

Traceback (most recent call last):
  File "/data/odoo/openerp/http.py", line 517, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/data/odoo/openerp/http.py", line 538, in dispatch
    result = self._call_function(**self.params)
  File "/data/odoo/openerp/http.py", line 294, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/data/odoo/openerp/service/model.py", line 113, in wrapper
    return f(dbname, *args, **kwargs)
  File "/data/odoo/openerp/http.py", line 291, in checked_call
    return self.endpoint(*a, **kw)
  File "/data/odoo/openerp/http.py", line 754, in __call__
    return self.method(*args, **kw)
  File "/data/odoo/openerp/http.py", line 387, in response_wrap
    response = f(*args, **kw)
  File "/data/odoo/addons/web/controllers/main.py", line 949, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "/data/odoo/addons/web/controllers/main.py", line 941, in _call_kw
    return getattr(request.registry.get(model), method)(request.cr, request.uid, *args, **kwargs)
  File "/data/odoo/openerp/api.py", line 237, in wrapper
    return old_api(self, *args, **kwargs)
  File "/data/odoo/openerp/api.py", line 391, in old_api
    result = new_api(recs, *args, **kwargs)
  File "/data/odoo/openerp/api.py", line 395, in new_api
    result = [method(rec, *args, **kwargs) for rec in self]
  File "/data/odoo/addons/ssmr_kanban/ssmr_kanban.py", line 73, in write
    obj_ordertracking.create({'workstation': self.id, 'stage': 'wait'})
  File "/data/odoo/openerp/api.py", line 235, in wrapper
    return new_api(self, *args, **kwargs)
  File "/data/odoo/addons/ssmr_kanban/ssmr_kanban.py", line 678, in create
    email_template.send_mail(res.id, force_send=True)
  File "/data/odoo/openerp/api.py", line 235, in wrapper
    return new_api(self, *args, **kwargs)
  File "/data/odoo/openerp/api.py", line 507, in new_api
    result = [method(self._model, cr, uid, id, *args, **kwargs) for id in self.ids]
  File "/data/odoo/addons/email_template/email_template.py", line 556, in send_mail
    msg_id = mail_mail.create(cr, uid, values, context=context)
  File "/data/odoo/openerp/api.py", line 237, in wrapper
    return old_api(self, *args, **kwargs)
  File "/data/odoo/addons/fetchmail/fetchmail.py", line 298, in create
    res = super(mail_mail, self).create(cr, uid, values, context=context)
  File "/data/odoo/openerp/api.py", line 237, in wrapper
    return old_api(self, *args, **kwargs)
  File "/data/odoo/addons/mail/mail_mail.py", line 84, in create
    return super(mail_mail, self).create(cr, uid, values, context=context)
  File "/data/odoo/openerp/api.py", line 237, in wrapper
    return old_api(self, *args, **kwargs)
  File "/data/odoo/openerp/api.py", line 332, in old_api
    result = method(recs, *args, **kwargs)
  File "/data/odoo/openerp/models.py", line 3994, in create
    record = self.browse(self._create(old_vals))
  File "/data/odoo/openerp/api.py", line 235, in wrapper
    return new_api(self, *args, **kwargs)
  File "/data/odoo/openerp/api.py", line 464, in new_api
    result = method(self._model, cr, uid, *args, **kwargs)
  File "/data/odoo/openerp/models.py", line 4050, in _create
    record_id = self.pool[table].create(cr, user, tocreate[table], context=context)
  File "/data/odoo/openerp/api.py", line 237, in wrapper
    return old_api(self, *args, **kwargs)
  File "/data/odoo/addons/mail/mail_message.py", line 802, in create
    values['record_name'] = self._get_record_name(cr, uid, values, context=context)
  File "/data/odoo/openerp/api.py", line 237, in wrapper
    return old_api(self, *args, **kwargs)
  File "/data/odoo/addons/mail/mail_message.py", line 772, in _get_record_name
    return self.pool[values['model']].name_get(cr, SUPERUSER_ID, [values['res_id']], context=context)[0][1]
  File "/data/odoo/openerp/api.py", line 237, in wrapper
    return old_api(self, *args, **kwargs)
  File "/data/odoo/openerp/api.py", line 360, in old_api
    result = method(recs, *args, **kwargs)
  File "/data/odoo/openerp/models.py", line 1669, in name_get
    result.append((record.id, convert(record[name])))
  File "/data/odoo/openerp/models.py", line 5486, in __getitem__
    return self._fields[key].__get__(self, type(self))
  File "/data/odoo/openerp/fields.py", line 764, in __get__
    return record._cache[self]
  File "/data/odoo/openerp/models.py", line 5820, in __getitem__
    return value.get() if isinstance(value, SpecialValue) else value
  File "/data/odoo/openerp/fields.py", line 53, in get
    raise self.exception
MissingError: ('MissingError', u'One of the documents you are trying to access has been deleted, please try again after refreshing.')