Hi!

I had installed module mass_edditing  for odoo 9 in /var/odoo/addons, where I have all my modules, but when I try to execute in Settings > General Settings > Mass editing > Mass editing 

I have the next error:

 Server Error

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 651, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 688, in dispatch
    result = self._call_function(**self.params)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 324, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/service/model.py", line 118, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 317, in checked_call
    result = self.endpoint(*a, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 967, in __call__
    return self.method(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 517, in response_wrap
    response = f(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/web/controllers/main.py", line 1167, in load
    action = request.session.model(action_type).read([action_id], False, ctx)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 1072, in proxy
    result = meth(cr, request.uid, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper
    return old_api(self, *args, **kwargs)
  File "/var/ /addons/web_debranding/models/ir_actions.py", line 11, in read
    cr, uid, ids, fields=fields, context=context, load=load)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper
    return old_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/ir/ir_actions.py", line 370, in read
    results = super(ir_actions_act_window, self).read(cr, uid, ids, fields=fields, context=context, load=load)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 250, in wrapper
    return old_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/models.py", line 3209, in read
    result = BaseModel.read(records, fields, load=load)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 248, in wrapper
    return new_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/models.py", line 3244, in read
    self._read_from_database(stored, inherited)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 248, in wrapper
    return new_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/models.py", line 3435, in _read_from_database
    res2 = self._columns[f].get(cr, self._model, ids, f, user, context=context, values=result)
  File "/usr/lib/python2.7/dist-packages/openerp/osv/fields.py", line 1506, in get
    result = self._fnct(obj, cr, uid, ids, name, self._arg, context)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/ir/ir_actions.py", line 310, in _search_view
    field_get = self.pool[act.res_model].fields_view_get(cr, uid,
  File "/usr/lib/python2.7/dist-packages/openerp/modules/registry.py", line 84, in __getitem__
    return self.models[model_name]
KeyError: u'mass.object'

I had installed this module in Odoo 8 and it works perfectly.

Thanks