Could not load 'debug' callback plugin

Hello,

I upgraded to ansible-core 2.21.2 and tried to execute a simple playbook.

The following error message came up:

[ERROR]: Could not load 'debug' callback plugin.

I have this line in /etc/ansible/ansible.cfg:

stdout_callback=debug

Was the debug callback plugin removed in recent versions?

Did you use debug or ansible.posix.debug?
What do you get for something basic, like

utoddl@tango:~$ ANSIBLE_LOAD_CALLBACK_PLUGINS=1 \
> ANSIBLE_STDOUT_CALLBACK=ansible.posix.debug \
> ansible localhost -m ansible.builtin.debug -a 'var=group_names'

PLAY [Ansible Ad-Hoc] ***********************************

TASK [ansible.builtin.debug] ****************************
ok: [localhost] => {
    "group_names": []
}

PLAY RECAP **********************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Hi @utoddl

Thanks. I did not know that debug was part of ansible.posix.

I had to install the collection:

ansible-galaxy collection install ansible.posix

Now it works again.
I think it was installed before as part of the ansible package and now I am only using ansible-core which means I need to install all collections manually.