I am getting the following error while creating another website in Odoo; the current website is working perfectly, this error only when adding another website;

Odoo Server Error
Traceback (most recent call last):
  File "/opt/uveostaa/15.0/odoo/odoo/tools/cache.py", line 85, in lookup
    r = d[key]
  File "/opt/uveostaa/15.0/odoo/odoo/tools/func.py", line 71, in wrapper
    return func(self, *args, **kwargs)
  File "/opt/uveostaa/15.0/odoo/odoo/tools/lru.py", line 34, in __getitem__
    a = self.d[obj]
KeyError: ('ir.model.data', , 'website.main_menu')

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

Traceback (most recent call last):
  File "/opt/uveostaa/15.0/odoo/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/opt/uveostaa/15.0/odoo/odoo/http.py", line 687, in dispatch
    result = self._call_function(**self.params)
  File "/opt/uveostaa/15.0/odoo/odoo/http.py", line 359, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/opt/uveostaa/15.0/odoo/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/opt/uveostaa/15.0/odoo/odoo/http.py", line 348, in checked_call
    result = self.endpoint(*a, **kw)
  File "/opt/uveostaa/15.0/odoo/odoo/http.py", line 916, in __call__
    return self.method(*args, **kw)
  File "/opt/uveostaa/15.0/odoo/odoo/http.py", line 535, in response_wrap
    response = f(*args, **kw)
  File "/opt/uveostaa/15.0/odoo/addons/web/controllers/main.py", line 1347, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "/opt/uveostaa/15.0/odoo/addons/web/controllers/main.py", line 1339, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/opt/uveostaa/15.0/odoo/odoo/api.py", line 462, in call_kw
    result = _call_kw_model_create(method, model, args, kwargs)
  File "/opt/uveostaa/15.0/odoo/odoo/api.py", line 442, in _call_kw_model_create
    result = method(recs, *args, **kwargs)
  File "", line 2, in create
  File "/opt/uveostaa/15.0/odoo/odoo/api.py", line 391, in _model_create_single
    return create(self, arg)
  File "/opt/uveostaa/15.0/odoo/addons/website/models/website.py", line 192, in create
    res._bootstrap_homepage()
  File "/opt/uveostaa/15.0/odoo/addons/website/models/website.py", line 629, in _bootstrap_homepage
    default_menu = self.env.ref('website.main_menu')
  File "/opt/uveostaa/15.0/odoo/odoo/api.py", line 578, in ref
    res_model, res_id = self['ir.model.data']._xmlid_to_res_model_res_id(
  File "/opt/uveostaa/15.0/odoo/odoo/addons/base/models/ir_model.py", line 1935, in _xmlid_to_res_model_res_id
    return self._xmlid_lookup(xmlid)[1:3]
  File "", line 2, in _xmlid_lookup
  File "/opt/uveostaa/15.0/odoo/odoo/tools/cache.py", line 90, in lookup
    value = d[key] = self.method(*args, **kwargs)
  File "/opt/uveostaa/15.0/odoo/odoo/addons/base/models/ir_model.py", line 1928, in _xmlid_lookup
    raise ValueError('External ID not found in the system: %s' % xmlid)
Exception

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

Traceback (most recent call last):
  File "/opt/uveostaa/15.0/odoo/odoo/http.py", line 643, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/opt/uveostaa/15.0/odoo/odoo/http.py", line 301, in _handle_exception
    raise exception.with_traceback(None) from new_cause
ValueError: External ID not found in the system: website.main_menu

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Any guidance in solving the above error will be highly appreciated.