v4.26, produces no output, errors in the log

I just upgraded pgAdmin from 4.24 to 4.26 (python wheel install) and almost all result tabs are now blank.

Neither Query nor Explain produce any result. I cleared all chrome cache (cookies, session/local storage), restarted the backend with no success.

I rolled back to 4.24 and everything works as before.

Version: 4.26
Copyright (C) 2013 - 2020, The pgAdmin Development Team
Python Version: 3.8.2 (default, Jul 16 2020, 14:00:26) [GCC 9.3.0]
Flask Version: 1.0.2
Application Mode: Desktop
Current User: pgadmin4@pgadmin.org

OS: "20.04.1 LTS (Focal Fossa)"

The log is a repetition of the same error (see below)

===============================================

2020-10-08 12:25:39,125: ERROR  flask.app:      400 Bad Request: The CSRF session token is missing.
Traceback (most recent call last):
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 256, in protect
    validate_csrf(self._get_csrf_token())
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 94, in validate_csrf
    raise ValidationError('The CSRF session token is missing.')
wtforms.validators.ValidationError: The CSRF session token is missing.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask/app.py", line 1811, in full_dispatch_request
    rv = self.preprocess_request()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask/app.py", line 2087, in preprocess_request
    rv = func()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 224, in csrf_protect
    self.protect()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 259, in protect
    self._error_response(e.args[0])
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 302, in _error_response
    raise CSRFError(reason)
flask_wtf.csrf.CSRFError: 400 Bad Request: The CSRF session token is missing.
2020-10-08 13:01:37,714: ERROR  flask.app:      400 Bad Request: The CSRF session token is missing.
Traceback (most recent call last):
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 256, in protect
    validate_csrf(self._get_csrf_token())
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 94, in validate_csrf
    raise ValidationError('The CSRF session token is missing.')
wtforms.validators.ValidationError: The CSRF session token is missing.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask/app.py", line 1811, in full_dispatch_request
    rv = self.preprocess_request()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask/app.py", line 2087, in preprocess_request
    rv = func()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 224, in csrf_protect
    self.protect()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 259, in protect
    self._error_response(e.args[0])
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 302, in _error_response
    raise CSRFError(reason)
flask_wtf.csrf.CSRFError: 400 Bad Request: The CSRF session token is missing.
2020-10-08 13:01:42,712: ERROR  flask.app:      400 Bad Request: The CSRF session token is missing.
Traceback (most recent call last):
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 256, in protect
    validate_csrf(self._get_csrf_token())
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 94, in validate_csrf
    raise ValidationError('The CSRF session token is missing.')
wtforms.validators.ValidationError: The CSRF session token is missing.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask/app.py", line 1811, in full_dispatch_request
    rv = self.preprocess_request()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask/app.py", line 2087, in preprocess_request
    rv = func()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 224, in csrf_protect
    self.protect()
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 259, in protect
    self._error_response(e.args[0])
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 302, in _error_response
    raise CSRFError(reason)
flask_wtf.csrf.CSRFError: 400 Bad Request: The CSRF session token is missing.
2020-10-08 13:01:44,035: ERROR  flask.app:      400 Bad Request: The CSRF session token is missing.
Traceback (most recent call last):
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 256, in protect
    validate_csrf(self._get_csrf_token())
  File "/home/user/opt/pgadmin4/lib/python3.8/site-packages/flask_wtf/csrf.py", line 94, in validate_csrf
    raise ValidationError('The CSRF session token is missing.')
wtforms.validators.ValidationError: The CSRF session token is missing.