Error:
Odoo Server Error

Traceback (most recent call last):
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/http.py", line 654, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/http.py", line 312, in _handle_exception
    raise pycompat.reraise(type(exception), exception, sys.exc_info()[2])
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/tools/pycompat.py", line 87, in reraise
    raise value
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/http.py", line 696, in dispatch
    result = self._call_function(**self.params)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/http.py", line 344, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/service/model.py", line 97, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/http.py", line 337, in checked_call
    result = self.endpoint(*a, **kw)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/http.py", line 939, in __call__
    return self.method(*args, **kw)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/http.py", line 517, in response_wrap
    response = f(*args, **kw)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/addons/web/controllers/main.py", line 962, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/addons/web/controllers/main.py", line 954, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/api.py", line 749, in call_kw
    return _call_kw_multi(method, model, args, kwargs)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/api.py", line 736, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/addons/account_reports/models/account_report.py", line 449, in get_report_informations
    self._apply_date_filter(options)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/addons/account_reports/models/account_report.py", line 949, in _apply_date_filter
    period_vals = self._get_dates_period(options, date_from, date_to, period_type)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/addons/account_reports/models/account_report.py", line 773, in _get_dates_period
    company_fiscalyear_dates = self.env.user.company_id.compute_fiscalyear_dates(date)
  File "/usr/share/odoo_venv/lib/python3.6/site-packages/odoo/addons/account/models/company.py", line 200, in compute_fiscalyear_dates
    date_str = current_date.strftime(DEFAULT_SERVER_DATE_FORMAT)
AttributeError: 'NoneType' object has no attribute 'strftime'

We faced with the server error since 2019. 

It impacts different users with the different browsers (Safari less, Chrome more).

The error happened while using Accounting module, Parther/Customer/Ledger report.

Developer promises that he did not change the code connected to date_format.

The bug may be fixed while using 'Incognito' mode in browser.

Enterprise edition.