I am learning Odoo from odoo 15 essentials book. Once i reached page no.125 which is about Adding menu items. I've edited the XML file in the views directory as mentioned in the book. then when I am trying to upgrade the module it throwing errors..
the following is the XML:

  Library Books library.book tree,form


These are the errors I am getting when upgrading the module

Traceback (most recent call last):
  File "/home/molham/work15/odoo/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/home/molham/work15/odoo/odoo/http.py", line 698, in dispatch
    result = self._call_function(**self.params)
  File "/home/molham/work15/odoo/odoo/http.py", line 368, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/home/molham/work15/odoo/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/home/molham/work15/odoo/odoo/http.py", line 357, in checked_call
    result = self.endpoint(*a, **kw)
  File "/home/molham/work15/odoo/odoo/http.py", line 921, in __call__
    return self.method(*args, **kw)
  File "/home/molham/work15/odoo/odoo/http.py", line 546, in response_wrap
    response = f(*args, **kw)
  File "/home/molham/work15/odoo/addons/web/controllers/main.py", line 1328, in call_button
    action = self._call_kw(model, method, args, kwargs)
  File "/home/molham/work15/odoo/addons/web/controllers/main.py", line 1316, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/home/molham/work15/odoo/odoo/api.py", line 464, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/home/molham/work15/odoo/odoo/api.py", line 451, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "", line 2, in button_immediate_upgrade
  File "/home/molham/work15/odoo/odoo/addons/base/models/ir_module.py", line 72, in check_and_log
    return method(self, *args, **kwargs)
  File "/home/molham/work15/odoo/odoo/addons/base/models/ir_module.py", line 643, in button_immediate_upgrade
    return self._button_immediate_function(type(self).button_upgrade)
  File "/home/molham/work15/odoo/odoo/addons/base/models/ir_module.py", line 580, in _button_immediate_function
    registry = modules.registry.Registry.new(self._cr.dbname, update_module=True)
  File "/home/molham/work15/odoo/odoo/modules/registry.py", line 87, in new
    odoo.modules.load_modules(registry, force_demo, status, update_module)
  File "/home/molham/work15/odoo/odoo/modules/loading.py", line 470, in load_modules
    processed_modules += load_marked_modules(cr, graph,
  File "/home/molham/work15/odoo/odoo/modules/loading.py", line 363, in load_marked_modules
    loaded, processed = load_module_graph(
  File "/home/molham/work15/odoo/odoo/modules/loading.py", line 222, in load_module_graph
    load_data(cr, idref, mode, kind='data', package=package)
  File "/home/molham/work15/odoo/odoo/modules/loading.py", line 69, in load_data
    tools.convert_file(cr, package.name, filename, idref, mode, noupdate, kind)
  File "/home/molham/work15/odoo/odoo/tools/convert.py", line 744, in convert_file
    convert_csv_import(cr, module, pathname, fp.read(), idref, mode, noupdate)
  File "/home/molham/work15/odoo/odoo/tools/convert.py", line 786, in convert_csv_import
    result = env[model].load(fields, datas)
  File "/home/molham/work15/odoo/odoo/models.py", line 1101, in load
    if isinstance(model_fields[field_path[0]], odoo.fields.Many2one):
Exception

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

Traceback (most recent call last):
  File "/home/molham/work15/odoo/odoo/http.py", line 654, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/home/molham/work15/odoo/odoo/http.py", line 301, in _handle_exception
    raise exception.with_traceback(None) from new_cause
KeyError: 'perm_'


What could be the issue?
Thanks in advance.