Errore:
Odoo Server Error

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/odoo/tools/cache.py", line 88, in lookup
    r = d[key]
  File "/usr/lib/python3/dist-packages/odoo/tools/func.py", line 69, in wrapper
    return func(self, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/tools/lru.py", line 44, in __getitem__
    a = self.d[obj].me
KeyError: ('ir.model.data', <function IrModelData.xmlid_lookup at 0x7ffaf6c2c400>, 'sale.group_discount_per_so_line')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 656, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 314, in _handle_exception
    raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
  File "/usr/lib/python3/dist-packages/odoo/tools/pycompat.py", line 87, in reraise
    raise value
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 698, in dispatch
    result = self._call_function(**self.params)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 346, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/service/model.py", line 98, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 339, in checked_call
    result = self.endpoint(*a, **kw)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 941, in __call__
    return self.method(*args, **kw)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 519, in response_wrap
    response = f(*args, **kw)
  File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 963, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 955, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/usr/lib/python3/dist-packages/odoo/api.py", line 755, in call_kw
    return _call_kw_model(method, model, args, kwargs)
  File "/usr/lib/python3/dist-packages/odoo/api.py", line 728, in _call_kw_model
    result = method(recs, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/res_config.py", line 497, in default_get
    classified = self._get_classified_fields()
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/res_config.py", line 472, in _get_classified_fields
    groups.append((name, field_groups, ref(field.implied_group)))
  File "/usr/lib/python3/dist-packages/odoo/api.py", line 864, in ref
    return self['ir.model.data'].xmlid_to_object(xml_id, raise_if_not_found=raise_if_not_found)
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_model.py", line 1443, in xmlid_to_object
    t = self.xmlid_to_res_model_res_id(xmlid, raise_if_not_found)
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_model.py", line 1427, in xmlid_to_res_model_res_id
    return self.xmlid_lookup(xmlid)[1:3]
  File "<decorator-gen-25>", line 2, in xmlid_lookup
  File "/usr/lib/python3/dist-packages/odoo/tools/cache.py", line 93, in lookup
    value = d[key] = self.method(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_model.py", line 1416, in xmlid_lookup
    raise ValueError('External ID not found in the system: %s' % xmlid)
ValueError: External ID not found in the system: sale.group_discount_per_so_line

Qualche idea?

Grazie