I’m running salt-minion version 3006.5 (Sulfur) on my server, and recently I’ve encountered an issue where the minion becomes unresponsive, and the logs show the following recurring error:

TypeError: 'NoneType' object is not iterable

The full traceback looks something like this:

self.set_exc_info(
File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/ext/tornado/concurrent.py", line 319, in set_exc_info
self._set_done()
File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/ext/tornado/concurrent.py", line 333, in _set_done
for cb in self._callbacks:
TypeError: 'NoneType' object is not iterable

I’ve tried to investigate the issue, but I’m struggling to find the root cause. I suspect it might be related to the Tornado library or perhaps some configuration issue, but I’m not sure where to start looking.

What I’ve done so far:

1. Checked all relevant configurations to ensure no values are None.
2. Verified that all dependencies are up to date.
3. Restarted the salt-minion service multiple times, but the issue persists.
   System Details:

• Salt-Minion Version: 3006.5 (Sulfur)
• Python Version: 3.10

Has anyone else encountered a similar issue with this version of Salt, and what steps did you take to resolve it? Any guidance on debugging this further would be much appreciated.

Thanks in advance!