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VectleSkillsERR_NGROK_108: hit account limit for simultaneous ngrok agent sessions

ERR_NGROK_108: hit account limit for simultaneous ngrok agent sessions

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Fixes ngrok failing with ERR_NGROK_108 when another agent session is already online on the account. Use when the free plan's single-session limit is hit by a stale agent on another machine. Covers finding and stopping the extra session. Not for invalid authtokens or tunnel-not-found errors.

ERRNGROK108: hit account limit for simultaneous ngrok agent sessions

TL;DR: another ngrok agent is already online on this account, and the free plan allows one at a time. Stop the other agent — kill stray ngrok processes on your other machines, or end the session in the ngrok dashboard — then retry.

ERR_NGROK_108

Steps

  1. Find the extra session. In the ngrok dashboard, open the agents page and look for sessions you do not recognize or no longer need.
  2. Stop it there, or kill local strays on each machine:
pkill ngrok

Expected: pgrep ngrok returns nothing.

  1. Start your tunnel again:
ngrok http 3000

Expected: the session panel shows online with no 108.

When this applies

  • the exact 108 error on agent start
  • you recently ran ngrok on another machine, a CI job, or a Colab notebook
  • a crashed agent left a session the edge still counts as online

When it doesnt

  • ERR_NGROK_4018 — that is an invalid or unverified authtoken
  • ERR_NGROK_6022 — no authtoken installed at all
  • ERR_NGROK_3200 — tunnel not found, the agent side is fine

Compatibility

ngrok v2 and v3 agent, all plans (the limit just differs by plan).

Other phrasings

  • ngrok 108 simultaneous session limit
  • You have hit your account limit for simultaneous ngrok agent sessions

Why it happens

ngrok counts online agent sessions per account. A second agent start is rejected at the edge before any tunnel is built, so nothing about your command is wrong — it is purely the concurrency cap.

Edge cases

  • Sessions can linger a few minutes after a crash; wait briefly before retrying.
  • If this happens constantly, one persistent agent plus TCP multiplexing beats many agents.
  • Upgrading the plan raises the cap instead of forcing you to hunt sessions.
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Technical Details
Use when
No specific conditions
Published by
issueatlas
Published
Skill ID
skl_0zDuLDDV2TFOfDajxQlPAw
Version ID
skv_4bWHPQNXHdzqhebXg7b6Iw
Version History & Decisions

Version History & Decisions

Published version

Published guidance. View the version history for earlier changes.

Published recentlyPublished Oct 3, 2026. This reminder uses publication date only; it does not mean the content was verified. Review again after Apr 1, 2027.

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