Odoo 12 Server Error KeyError: 'crm.Stage' - odoo

Question

I am a starter in odoo. Can anyone help me to find a solution for the problem mentioned below?
In CRM Module I'm getting this below this error when I save any record in CRM Module, it was working fine for a while but idk after sometime when I create or change any record this error pops up
Error:
Odoo Server Error
Traceback (most recent call last):
File "/opt/odoo/odoo-12.0/odoo/http.py", line 656, in _handle_exception
return super(JsonRequest, self)._handle_exception(exception)
File "/opt/odoo/odoo-12.0/odoo/http.py", line 314, in _handle_exception
raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
File "/opt/odoo/odoo-12.0/odoo/tools/pycompat.py", line 87, in reraise
raise value
File "/opt/odoo/odoo-12.0/odoo/http.py", line 698, in dispatch
result = self._call_function(**self.params)
File "/opt/odoo/odoo-12.0/odoo/http.py", line 346, in _call_function
return checked_call(self.db, *args, **kwargs)
File "/opt/odoo/odoo-12.0/odoo/service/model.py", line 98, in wrapper
return f(dbname, *args, **kwargs)
File "/opt/odoo/odoo-12.0/odoo/http.py", line 339, in checked_call
result = self.endpoint(*a, **kw)
File "/opt/odoo/odoo-12.0/odoo/http.py", line 941, in __call__
return self.method(*args, **kw)
File "/opt/odoo/odoo-12.0/odoo/http.py", line 519, in response_wrap
response = f(*args, **kw)
File "/opt/odoo/odoo-12.0/addons/web/controllers/main.py", line 962, in call_kw
return self._call_kw(model, method, args, kwargs)
File "/opt/odoo/odoo-12.0/addons/web/controllers/main.py", line 954, in _call_kw
return call_kw(request.env[model], method, args, kwargs)
File "/opt/odoo/odoo-12.0/odoo/api.py", line 757, in call_kw
return _call_kw_model_create(method, model, args, kwargs)
File "/opt/odoo/odoo-12.0/odoo/api.py", line 737, in _call_kw_model_create
result = method(recs, *args, **kwargs)
File "<decorator-gen-260>", line 2, in create
File "/opt/odoo/odoo-12.0/odoo/api.py", line 461, in _model_create_multi
return create(self, [arg])
File "/opt/odoo/odoo-12.0/addons/base_automation/models/base_automation.py", line 228, in create
records = create.origin(self.with_env(actions.env), vals_list, **kw)
File "<decorator-gen-116>", line 2, in create
File "/opt/odoo/odoo-12.0/odoo/api.py", line 462, in _model_create_multi
return create(self, arg)
File "/opt/odoo/odoo-12.0/addons/mail/models/mail_thread.py", line 272, in create
threads = super(MailThread, self).create(vals_list)
File "<decorator-gen-3>", line 2, in create
File "/opt/odoo/odoo-12.0/odoo/api.py", line 462, in _model_create_multi
return create(self, arg)
File "/opt/odoo/odoo-12.0/odoo/models.py", line 3534, in create
vals = self._add_missing_default_values(vals)
File "/opt/odoo/odoo-12.0/odoo/models.py", line 1700, in _add_missing_default_values
defaults = self.default_get(list(missing_defaults))
File "/opt/odoo/odoo-12.0/odoo/models.py", line 1168, in default_get
defaults[name] = field.default(self)
File "/opt/odoo/odoo-12.0/crm_internal_new/crm_extended/models/crm_lead_extended.py", line 37, in get_default_won_id1
return self.env['crm.Stage'].search([('name', '=', 'Won')]).id
File "/opt/odoo/odoo-12.0/odoo/api.py", line 831, in __getitem__
return self.registry[model_name]._browse((), self)
File "/opt/odoo/odoo-12.0/odoo/modules/registry.py", line 176, in __getitem__
return self.models[model_name]
KeyError: 'crm.Stage'