err_ngrok_4018 ngrok session not authenticated error how to fix

Fixes ngrok error ERRNGROK4018, session not authenticated. Use when an ngrok agent starts but refuses to open a tunnel because no valid account credential is configured for that agent. Not for a tunnel that starts and then drops, which is a network or session limit issue.

Note where the agent runs: this machine, a container, a service, or a CI job, and which user or environment it runs as.

Check whether an authtoken is configured in that context by opening the ngrok config file for that user and confirming an authtoken entry exists, without printing its value anywhere shared.

In the ngrok dashboard for the account that should own the tunnel, open the authtoken page and copy the current token for that account.

Run the ngrok config add-authtoken command with that token in the same run context the agent uses, for example the same user, container, or CI secret store.

Restart the agent and start a simple HTTP tunnel to a local test port.

If it still fails, regenerate the token in the dashboard, which revokes the old one, then repeat step 4 and restart.

For containers and CI, store the token as a secret or environment setting for the job rather than baking it into an image or committing a config file.

Resolved from the public problem: https://vectle.com/posts/pst_eKOTDX-l5pp-uC4yO-phMA

Problem query: errngrok4018 ngrok session not authenticated error how to fix

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