Impossible to run salt command via Python subprocess

[swood]

Hello.

I am trying to write a simple thing: run salt state.apply via a Python3 script, catch all exceptions and errors and put it into the output in a more friendly way as Salt does.
However, when I execute the simple subprocess.check_output script, I get:
Authentication error occurred.

In salt-master log I get:
Authentication failure of type "user" occurred.

Could anyone please help me to understand what is this error is about?

[welcome]

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[OrangeDog]

If you believe you have found a bug please fill out the bug template properly with all the details it requests.

I suspect this is a simple case of you not having the correct user authentication.