atal: [10.21.21.11]: FAILED! =>                                                                                                                                                                                   
  msg: |-                                                                                                                                                                                                          
    The task includes an option with an undefined variable. The error was: 'ansible.vars.hostvars.HostVarsVars object' has no attribute bla bla

Check the names in group_vars! They need to match the name of the group in the inventory file.

Check versions of ansible and dependencies. This was caused by the upgraded cryptography package (and using the old ansible version - 2.9.27) which was being source from /usr/local/lib/python3.10/dist-packages/. This fixed it:

sudo pip uninstall cryptography

to uninstall from system directory and then run this (notice no sudo) to install it in user's directory /home/user/.local/lib/python3.10/site-packages

pip install cryptography==2.6.1

Or just use a newer version of ansible which can use newer version of cryptography package.

• Ansible debug one variable
• Ansible debug all variables