[BUG] Using SaltGUI with 3006.1, error 401 when trying to login GUI.

Description
This bug report is created because I cannot connect to the SaltGUI GUI because an error 401. Many other users have the same issue with the version 3006.1.

Setup
SaltStack installed on RHEL 8 following all the requirements described in the installation part of the documentation. The RHEL 8 server in hosted in our VMWare farm.

Steps to Reproduce the behavior

1. Open to the SaltGUI GUI and try to connect with the dedicated created user,
2. Error 401 (authentication failed)

Expected behavior
User should be abble to login into the GUI.

Screenshots

Versions Report

Salt Version:
Salt: 3006.1

Python Version:
Python: 3.10.11 (main, May 5 2023, 02:31:54) [GCC 11.2.0]

Dependency Versions:
cffi: 1.14.6
cherrypy: unknown
dateutil: 2.8.1
docker-py: Not Installed
gitdb: Not Installed
gitpython: Not Installed
Jinja2: 3.1.2
libgit2: Not Installed
looseversion: 1.0.2
M2Crypto: Not Installed
Mako: Not Installed
msgpack: 1.0.2
msgpack-pure: Not Installed
mysql-python: Not Installed
packaging: 22.0
pycparser: 2.21
pycrypto: Not Installed
pycryptodome: 3.9.8
pygit2: Not Installed
python-gnupg: 0.4.8
PyYAML: 5.4.1
PyZMQ: 23.2.0
relenv: 0.12.3
smmap: Not Installed
timelib: 0.2.4
Tornado: 4.5.3
ZMQ: 4.3.4

System Versions:
dist: rhel 8.8 Ootpa
locale: utf-8
machine: x86_64
release: 4.18.0-477.10.1.el8_8.x86_64
system: Linux
version: Red Hat Enterprise Linux 8.8 Ootpa

Requirement already satisfied: cherrypy in /opt/saltstack/salt/lib/python3.10/site-packages (18.6.1)
Requirement already satisfied: cheroot>=8.2.1 in /opt/saltstack/salt/lib/python3.10/site-packages (from cherrypy) (8.5.2)
Requirement already satisfied: portend>=2.1.1 in /opt/saltstack/salt/lib/python3.10/site-packages (from cherrypy) (2.4)
Requirement already satisfied: more-itertools in /opt/saltstack/salt/lib/python3.10/site-packages (from cherrypy) (5.0.0)
Requirement already satisfied: zc.lockfile in /opt/saltstack/salt/lib/python3.10/site-packages (from cherrypy) (1.4)
Requirement already satisfied: jaraco.collections in /opt/saltstack/salt/lib/python3.10/site-packages (from cherrypy) (3.4.0)
Requirement already satisfied: six>=1.11.0 in /opt/saltstack/salt/lib/python3.10/site-packages (from cheroot>=8.2.1->cherrypy) (1.16.0)
Requirement already satisfied: jaraco.functools in /opt/saltstack/salt/lib/python3.10/site-packages (from cheroot>=8.2.1->cherrypy) (2.0)
Requirement already satisfied: tempora>=1.8 in /opt/saltstack/salt/lib/python3.10/site-packages (from portend>=2.1.1->cherrypy) (4.1.1)
Requirement already satisfied: jaraco.text in /opt/saltstack/salt/lib/python3.10/site-packages (from jaraco.collections->cherrypy) (3.5.1)
Requirement already satisfied: jaraco.classes in /opt/saltstack/salt/lib/python3.10/site-packages (from jaraco.collections->cherrypy) (3.2.1)
Requirement already satisfied: setuptools in /opt/saltstack/salt/lib/python3.10/site-packages (from zc.lockfile->cherrypy) (65.7.0)
Requirement already satisfied: pytz in /opt/saltstack/salt/lib/python3.10/site-packages (from tempora>=1.8->portend>=2.1.1->cherrypy) (2022.1)

Additional context

This issue may only concern the salt-api part, as the SaltGUI worked fine for many users before upgrading to 3006.1, without any changes made on the SaltGUI part.

Many thanks for your help and reply to this bug report,
Regards,
Jean

Start by reproducing the SaltGUI login failure with Salt 3006.1 on RHEL 8 and inspect the salt-api authentication configuration and logs around the 401 response. The issue is resolved when the dedicated user can authenticate to SaltGUI successfully without changing the GUI.