metadata issue on MOs

RPC_ERROR
Odoo Server Error
Traceback (most recent call last):
  File "/opt/odoo/odoo/odoo/models.py", line 5199, in ensure_one
    _id, = self._ids
ValueError: too many values to unpack (expected 1)

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/odoo/odoo/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/opt/odoo/odoo/odoo/http.py", line 687, in dispatch
    result = self._call_function(**self.params)
  File "/opt/odoo/odoo/odoo/http.py", line 359, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/opt/odoo/odoo/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/opt/odoo/odoo/odoo/http.py", line 348, in checked_call
    result = self.endpoint(*a, **kw)
  File "/opt/odoo/odoo/odoo/http.py", line 916, in __call__
    return self.method(*args, **kw)
  File "/opt/odoo/odoo/odoo/http.py", line 535, in response_wrap
    response = f(*args, **kw)
  File "/opt/odoo/odoo/addons/web/controllers/main.py", line 1347, in call_button
    action = self._call_kw(model, method, args, kwargs)
  File "/opt/odoo/odoo/addons/web/controllers/main.py", line 1335, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/opt/odoo/odoo/odoo/api.py", line 464, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/opt/odoo/odoo/odoo/api.py", line 451, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "/opt/odoo/customized_addons/zip_mrp_quality/models/mrp_workorder.py", line 55, in action_next
    self.update_quality_check_meta_data()
  File "/opt/odoo/customized_addons/zip_mrp_quality/models/mrp_workorder.py", line 46, in update_quality_check_meta_data
    meta_characteristic.name,
  File "/opt/odoo/odoo/odoo/fields.py", line 1050, in __get__
    record.ensure_one()
  File "/opt/odoo/odoo/odoo/models.py", line 5202, in ensure_one
    raise ValueError("Expected singleton: %s" % self)
Exception

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/odoo/odoo/odoo/http.py", line 643, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/opt/odoo/odoo/odoo/http.py", line 301, in _handle_exception
    raise exception.with_traceback(None) from new_cause
ValueError: Expected singleton: zip_product.characteristic(751614, 751615)