For me this error occurred as an side effect of the following backend error below. And solution for this was to upgrade `resource` addon. This is a core addon and looks like it had a bug in one of previous v13 releases.

```

2021-06-01 00:22:36,813 1 INFO *** odoo.addons.base.models.ir_ui_view: Field `tz` does not exist

Error context:
View `hr.leave.view.form.manager`
[view_id: 4368, xml_id: hr_holidays.hr_leave_view_form_manager, model: hr.leave, parent_id: 4365]
2021-06-01 00:22:36,813 1 ERROR *** odoo.http: Exception during JSON request handling.
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/odoo/http.py", line 624, in _handle_exception
return super(JsonRequest, self)._handle_exception(exception)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 310, in _handle_exception
raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
File "/usr/lib/python3/dist-packages/odoo/tools/pycompat.py", line 14, in reraise
raise value
File "/usr/lib/python3/dist-packages/odoo/http.py", line 669, in dispatch
result = self._call_function(**self.params)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 350, in _call_function
return checked_call(self.db, *args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/service/model.py", line 94, in wrapper
return f(dbname, *args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 339, in checked_call
result = self.endpoint(*a, **kw)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 915, in __call__
return self.method(*args, **kw)
File "/usr/lib/python3/dist-packages/odoo/http.py", line 515, in response_wrap
response = f(*args, **kw)
File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 1322, in call_kw
return self._call_kw(model, method, args, kwargs)
File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 1314, in _call_kw
return call_kw(request.env[model], method, args, kwargs)
File "/usr/lib/python3/dist-packages/odoo/api.py", line 383, in call_kw
result = _call_kw_model(method, model, args, kwargs)
File "/usr/lib/python3/dist-packages/odoo/api.py", line 356, in _call_kw_model
result = method(recs, *args, **kwargs)
File "/usr/lib/python3/dist-packages/odoo/models.py", line 1441, in load_views
for [v_id, v_type] in views
File "/usr/lib/python3/dist-packages/odoo/models.py", line 1441, in
for [v_id, v_type] in views
File "/usr/lib/python3/dist-packages/odoo/addons/mail/models/mail_thread.py", line 410, in fields_view_get
res = super(MailThread, self).fields_view_get(view_id=view_id, view_type=view_type, toolbar=toolbar, submenu=submenu)
File "/usr/lib/python3/dist-packages/odoo/addons/web/models/models.py", line 206, in fields_view_get
r = super().fields_view_get(view_id, view_type, toolbar, submenu)
File "/usr/lib/python3/dist-packages/odoo/models.py", line 1528, in fields_view_get
xarch, xfields = View.postprocess_and_fields(self._name, etree.fromstring(result['arch']), view_id)
File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_ui_view.py", line 987, in postprocess_and_fields
self.raise_view_error(message, view_id)
File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_ui_view.py", line 614, in raise_view_error
raise ValueError(message)
ValueError: Field `tz` does not exist

Error context:
View `hr.leave.view.form.manager`
[view_id: 4368, xml_id: hr_holidays.hr_leave_view_form_manager, model: hr.leave, parent_id: 4365]
```