I installed Odoo11 today and was configuring POS when i got these errors.Please help me fix

[sandhya834]

Point of sale for odoo11 generates error while configuration.Please help.I am new to odoo.just installed odoo11 and its throwing these errors.
Error:
Odoo Server Error

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/odoo/tools/cache.py", line 84, in lookup
r = d[key]
File "/usr/lib/python3/dist-packages/odoo/tools/func.py", line 68, 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 0x7ff0812bb158>, 'point_of_sale.fruits_vegetables')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/odoo/tools/safe_eval.py", line 348, in safe_eval
return unsafe_eval(c, globals_dict, locals_dict)
File "", line 1, in
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 724, in id_get
res = self.model_id_get(id_str, raise_if_not_found)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 730, in model_id_get
return self.env['ir.model.data'].xmlid_to_res_model_res_id(id_str, raise_if_not_found=raise_if_not_found)
File "/usr/lib/python3/dist-packages/odoo/addons/base/ir/ir_model.py", line 1316, in xmlid_to_res_model_res_id
return self.xmlid_lookup(xmlid)[1:3]
File "", line 2, in xmlid_lookup
File "/usr/lib/python3/dist-packages/odoo/tools/cache.py", line 89, in lookup
value = d[key] = self.method(*args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/addons/base/ir/ir_model.py", line 1305, in xmlid_lookup
raise ValueError('External ID not found in the system: %s' % xmlid)
ValueError: External ID not found in the system: point_of_sale.fruits_vegetables

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 741, in parse
self._tags[rec.tag](rec, de, mode=mode)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 641, in _tag_record
f_val = _eval_xml(self, field, self.env)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 113, in _eval_xml
return safe_eval(a_eval, idref2)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 28, in
safe_eval = lambda expr, ctx={}: s_eval(expr, ctx, nocopy=True)
File "/usr/lib/python3/dist-packages/odoo/tools/safe_eval.py", line 371, in safe_eval
pycompat.reraise(ValueError, ValueError('%s: "%s" while evaluating\n%r' % (ustr(type(e)), ustr(e), expr)), exc_info[2])
File "/usr/lib/python3/dist-packages/odoo/tools/pycompat.py", line 86, in reraise
raise value.with_traceback(tb)
File "/usr/lib/python3/dist-packages/odoo/tools/safe_eval.py", line 348, in safe_eval
return unsafe_eval(c, globals_dict, locals_dict)
File "", line 1, in
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 724, in id_get
res = self.model_id_get(id_str, raise_if_not_found)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 730, in model_id_get
return self.env['ir.model.data'].xmlid_to_res_model_res_id(id_str, raise_if_not_found=raise_if_not_found)
File "/usr/lib/python3/dist-packages/odoo/addons/base/ir/ir_model.py", line 1316, in xmlid_to_res_model_res_id
return self.xmlid_lookup(xmlid)[1:3]
File "", line 2, in xmlid_lookup
File "/usr/lib/python3/dist-packages/odoo/tools/cache.py", line 89, in lookup
value = d[key] = self.method(*args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/addons/base/ir/ir_model.py", line 1305, in xmlid_lookup
raise ValueError('External ID not found in the system: %s' % xmlid)
ValueError: <class 'ValueError'>: "External ID not found in the system: point_of_sale.fruits_vegetables" while evaluating
"[(6, 0, [ref('point_of_sale.fruits_vegetables')])]"

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/odoo/http.py", line 646, in _handle_exception
return super(JsonRequest, self)._handle_exception(exception)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 307, 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 683, in dispatch
result = self._call_function(**self.params)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 339, in _call_function
return checked_call(self.db, *args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/service/model.py", line 97, in wrapper
return f(dbname, *args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 332, in checked_call
result = self.endpoint(*a, **kw)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 927, in call
return self.method(*args, **kw)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 512, in response_wrap
response = f(*args, **kw)
File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 924, in call_kw
return self._call_kw(model, method, args, kwargs)
File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 916, in _call_kw
return call_kw(request.env[model], method, args, kwargs)
File "/usr/lib/python3/dist-packages/odoo/api.py", line 687, in call_kw
return call_kw_model(method, model, args, kwargs)
File "/usr/lib/python3/dist-packages/odoo/api.py", line 672, in call_kw_model
result = method(recs, *args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/addons/point_of_sale/models/pos_config.py", line 347, in create
pos_config.sudo()._check_modules_to_install()
File "/usr/lib/python3/dist-packages/odoo/addons/point_of_sale/models/pos_config.py", line 385, in _check_modules_to_install
module_to_install.button_immediate_install()
File "", line 2, in button_immediate_install
File "/usr/lib/python3/dist-packages/odoo/addons/base/module/module.py", line 71, in check_and_log
return method(self, *args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/addons/base/module/module.py", line 448, in button_immediate_install
return self._button_immediate_function(type(self).button_install)
File "/usr/lib/python3/dist-packages/odoo/addons/base/module/module.py", line 541, in _button_immediate_function
modules.registry.Registry.new(self._cr.dbname, update_module=True)
File "/usr/lib/python3/dist-packages/odoo/modules/registry.py", line 85, in new
odoo.modules.load_modules(registry._db, force_demo, status, update_module)
File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 343, in load_modules
loaded_modules, update_module)
File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 242, in load_marked_modules
loaded, processed = load_module_graph(cr, graph, progressdict, report=report, skip_modules=loaded_modules, perform_checks=perform_checks)
File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 159, in load_module_graph
_load_data(cr, module_name, idref, mode, kind='demo')
File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 94, in _load_data
tools.convert_file(cr, module_name, filename, idref, mode, noupdate, kind, report)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 788, in convert_file
convert_xml_import(cr, module, fp, idref, mode, noupdate, report)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 849, in convert_xml_import
obj.parse(doc.getroot(), mode=mode)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 748, in parse
exc_info[2]
File "/usr/lib/python3/dist-packages/odoo/tools/pycompat.py", line 86, in reraise
raise value.with_traceback(tb)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 741, in parse
self._tags[rec.tag](rec, de, mode=mode)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 641, in _tag_record
f_val = _eval_xml(self, field, self.env)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 113, in _eval_xml
return safe_eval(a_eval, idref2)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 28, in
safe_eval = lambda expr, ctx={}: s_eval(expr, ctx, nocopy=True)
File "/usr/lib/python3/dist-packages/odoo/tools/safe_eval.py", line 371, in safe_eval
pycompat.reraise(ValueError, ValueError('%s: "%s" while evaluating\n%r' % (ustr(type(e)), ustr(e), expr)), exc_info[2])
File "/usr/lib/python3/dist-packages/odoo/tools/pycompat.py", line 86, in reraise
raise value.with_traceback(tb)
File "/usr/lib/python3/dist-packages/odoo/tools/safe_eval.py", line 348, in safe_eval
return unsafe_eval(c, globals_dict, locals_dict)
File "", line 1, in
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 724, in id_get
res = self.model_id_get(id_str, raise_if_not_found)
File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 730, in model_id_get
return self.env['ir.model.data'].xmlid_to_res_model_res_id(id_str, raise_if_not_found=raise_if_not_found)
File "/usr/lib/python3/dist-packages/odoo/addons/base/ir/ir_model.py", line 1316, in xmlid_to_res_model_res_id
return self.xmlid_lookup(xmlid)[1:3]
File "", line 2, in xmlid_lookup
File "/usr/lib/python3/dist-packages/odoo/tools/cache.py", line 89, in lookup
value = d[key] = self.method(*args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/addons/base/ir/ir_model.py", line 1305, in xmlid_lookup
raise ValueError('External ID not found in the system: %s' % xmlid)
odoo.tools.convert.ParseError: "<class 'ValueError'>: "External ID not found in the system: point_of_sale.fruits_vegetables" while evaluating
"[(6, 0, [ref('point_of_sale.fruits_vegetables')])]"" while parsing /usr/lib/python3/dist-packages/odoo/addons/pos_restaurant/data/pos_restaurant_demo.xml:8, near

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