Slack error two_factor_setup_required: Two-factor setup is required

The workspace enforces two-factor authentication, and the user behind the token has not completed 2FA setup, so Slack refuses to act on their behalf. The reference description on chat.postMessage is the terse "Two factor setup is required." This is an account-state error, not an API-usage error: nothing about your request is wrong, and no request parameter can fix it.

You will effectively only see this with user tokens, because it is a property of a human account. Bot users do not go through 2FA enrollment. That makes the error a strong hint about your architecture: an integration that can be blocked by one employee's incomplete security enrollment is an integration riding on a personal credential, with all the fragility that implies (see also account_inactive for the offboarding variant of the same problem).

The fix happens in Slack, not in code: the user signs in and completes two-factor enrollment as their admin requires, after which the same token works again. Your app's job is merely to fail gracefully and tell the right person why their connected Slack account has stopped working.

{"ok": false, "error": "two_factor_setup_required"}

Prefer bot tokens over user tokens for anything unattended; personal-account states (2FA, deactivation, revocation) then cannot interrupt service. Where user tokens are essential, monitor for auth-family errors per user and notify the specific owner instead of aggregating them into a generic failure metric.