Failed to create directory /var/lib/leapp/el8userspace//sys/fs/selinux: Read-only file system

I am trying to use ELevate for upgrading a CentOS 7 server to AlmaLinux 8. Have fixed some issues before upgrading. However, after running

leapp upgrade

the upgrading returns error

STDERR:
Failed to create directory /var/lib/leapp/el8userspace//sys/fs/selinux: Read-only file system
Failed to create directory /var/lib/leapp/el8userspace//sys/fs/selinux: Read-only file system
No matches found for the following disable plugin patterns: subscription-manager
Warning: Packages marked by Leapp for upgrade not found in repositories metadata: gpg-pubkey
RPM: warning: Generating 6 missing index(es), please wait...
Error: Transaction test error:
  file /usr/lib/python3.6/site-packages/__pycache__/six.cpython-36.opt-1.pyc from install of python3-six-1.11.0-8.el8.noarch conflicts with file from package python36-six-1.14.0-3.el7.noarch
  file /usr/lib/python3.6/site-packages/__pycache__/six.cpython-36.pyc from install of python3-six-1.11.0-8.el8.noarch conflicts with file from package python36-six-1.14.0-3.el7.noarch
  file /usr/lib/python3.6/site-packages/six.py from install of python3-six-1.11.0-8.el8.noarch conflicts with file from package python36-six-1.14.0-3.el7.noarch
  file /usr/lib/python3.6/site-packages/__pycache__/pyparsing.cpython-36.opt-1.pyc from install of python3-pyparsing-2.1.10-7.el8.noarch conflicts with file from package python36-pyparsing-2.4.0-1.el7.noarch
  file /usr/lib/python3.6/site-packages/__pycache__/pyparsing.cpython-36.pyc from install of python3-pyparsing-2.1.10-7.el8.noarch conflicts with file from package python36-pyparsing-2.4.0-1.el7.noarch
  file /usr/lib/python3.6/site-packages/pyparsing.py from install of python3-pyparsing-2.1.10-7.el8.noarch conflicts with file from package python36-pyparsing-2.4.0-1.el7.noarch

The system is definitely not read-only. I can add and remove files without any problem. And I found this topic, at the end, it’s saying The following error message can be safely ignored, this is not the root cause…

I wonder if it’s also applying to my case, and is it safe for rebooting now?
Thanks.