I've installed Odoo12 on ubuntu 18.04. Everything works fine but when I want to access general settings I get an error that the field snailmail_duplex does not exist?

Can't find this problem on google or this forum. What caused it and how can I fix it?

Error:
Odoo Server Error

Traceback (most recent call last):
File "/opt/odoo/odoo12/odoo/http.py", line 656, in _handle_exception
return super(JsonRequest, self)._handle_exception(exception)
File "/opt/odoo/odoo12/odoo/http.py", line 314, in _handle_exception
raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
File "/opt/odoo/odoo12/odoo/tools/pycompat.py", line 87, in reraise
raise value
File "/opt/odoo/odoo12/odoo/http.py", line 698, in dispatch
result = self._call_function(**self.params)
File "/opt/odoo/odoo12/odoo/http.py", line 346, in _call_function
return checked_call(self.db, *args, **kwargs)
File "/opt/odoo/odoo12/odoo/service/model.py", line 97, in wrapper
return f(dbname, *args, **kwargs)
File "/opt/odoo/odoo12/odoo/http.py", line 339, in checked_call
result = self.endpoint(*a, **kw)
File "/opt/odoo/odoo12/odoo/http.py", line 941, in __call__
return self.method(*args, **kw)
File "/opt/odoo/odoo12/odoo/http.py", line 519, in response_wrap
response = f(*args, **kw)
File "/opt/odoo/odoo12/addons/web/controllers/main.py", line 962, in call_kw
return self._call_kw(model, method, args, kwargs)
File "/opt/odoo/odoo12/addons/web/controllers/main.py", line 954, in _call_kw
return call_kw(request.env[model], method, args, kwargs)
File "/opt/odoo/odoo12/odoo/api.py", line 745, in call_kw
return _call_kw_model(method, model, args, kwargs)
File "/opt/odoo/odoo12/odoo/api.py", line 718, in _call_kw_model
result = method(recs, *args, **kwargs)
File "/opt/odoo/odoo12/odoo/models.py", line 1376, in load_views
for [v_id, v_type] in views
File "/opt/odoo/odoo12/odoo/models.py", line 1376, in <dictcomp>
for [v_id, v_type] in views
File "/opt/odoo/odoo12/odoo/addons/base/models/res_config.py", line 395, in fields_view_get
toolbar=toolbar, submenu=submenu)
File "/opt/odoo/odoo12/odoo/models.py", line 1462, in fields_view_get
xarch, xfields = View.postprocess_and_fields(self._name, etree.fromstring(result['arch']), view_id)
File "/opt/odoo/odoo12/odoo/addons/base/models/ir_ui_view.py", line 1096, in postprocess_and_fields
self.raise_view_error(message, view_id)
File "/opt/odoo/odoo12/odoo/addons/base/models/ir_ui_view.py", line 548, in raise_view_error
raise ValueError(message)
ValueError: Field `snailmail_duplex` does not exist

Error context:
View `n/a`
[view_id: n/a, xml_id: n/a, model: n/a, parent_id: n/a]