Concurrent session limit reached (429 concurrency-limit)
You might be here because: “A usage limit was reached. Wait a moment or review your plan” · “Concurrent session limit reached” · “it won’t let me launch another profile” · “says I already have sessions running but I don’t see any” · “429 concurrency-limit” · “how many sessions can I run at once” · “launch button does nothing / greyed out”
Short answer
Your plan allows a fixed number of sessions open at the same time, and you already have that many. Nothing is broken: end a session you started (or wait for one to finish), then launch again. The limit is per account, so a teammate’s sessions count too: ask them before you stop one of theirs.
Check first
- Signed in to the right account? Team members launch on the team owner’s plan, so the owner’s open sessions count.
- Open the Sessions tab and look for anything still running, including sessions that are still starting (“provisioning” counts against the limit).
- A session that was closed from a script or another computer may need a refresh before the app shows the slot as free.
- This sentence covers four limits. What were you doing? Launching a profile → sessions at once (Concurrent session limit reached (429 concurrency-limit)) or, after a plan change, After a downgrade only the most recently used profiles/proxies can launch; creating or duplicating a profile → Cannot create a profile: plan’s saved-profile limit reached; sending a message to the AI → ‘3 AI tasks are already running’ (AI task limit).
Likely causes and fixes
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You are at your plan’s limit. The server refuses the next launch with HTTP 429
concurrency-limit, title “Concurrent session limit reached”, detail “Account already has N active sessions; tier permits N”. The desktop app shows this as “A usage limit was reached. Wait a moment or review your plan, then try again.”. Limits per plan: Trial 1, Starter 1, Pro 3, Team 6, Scale 12; Enterprise is set by contract. Legacy Free is 1. Fix: stop a session you started and no longer need, then launch. -
A session is still open somewhere else. Sessions started from code or a second computer hold a slot until they are closed. If you started them, stop them from the Sessions tab, or close them from the code that started them. If a teammate or their script did, ask them, or wait for one to end.
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A session is stuck ending. A session counts until it reaches a terminal state. Wait a minute and refresh; if it still shows as running and you started it, use Stop on its row; if someone else did, ask them.
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You need more sessions at once. The only way past the limit is a plan with a higher number. To move to Starter, Pro or Team, open the dashboard → Billing → Choose a plan (self-serve). Scale and Enterprise, refunds, disputed charges and “I paid but the plan is not active” are handled by a person.
If it still fails
Press Talk to a person in this chat (or open Help) and include: the plan you are on, what the Sessions tab shows as running, and the exact message. If a session shows as running but cannot be stopped, that is something a person looks at directly.