After Effects MCP connection errors: not connected, timeouts and reconnects

This page covers every message that means Prism and After Effects are not talking: the panel is signed in but a call is refused, times out, or the bridge drops. First move: read the panel header, then do not re-run anything.

Not connected

Not connected · not-connected

You see: "After Effects MCP is not connected. Open the panel in After Effects (Window → Extensions → After Effects MCP) and sign in, wait for the Connected state, then retry…"

Meaning. No After Effects panel is signed in to this account. Nothing ran.

Fix. In After Effects open Window ▸ Extensions ▸ After Effects MCP and sign in.

Do not loop the call. The full message tells the AI client why: "Nothing was run and the project

and the project is unchanged.

header (Connecting…, Reconnecting…, Retry) means it is still working on it. 2. If the panel shows Sign in, sign in. See Sign-in errors if that fails. 3. Wait for Connected, then re-send the same call. It is valid as written. 4. If the panel shows Connected and the client still says not connected, check the panel's account row matches the account your AI client signed in with, then read more than one After Effects.

is unchanged. Retrying this call unchanged will fail identically until a human opens that panel — tell the user, do not loop."

Shows in: your AI client. The panel banner stays quiet, because from the panel's side nothing arrived.

The header states

It gives up only when the server itself refuses the bridge (close code 4001 or 4003, a sign-in or plan refusal) five times in a row. The log then reads "MCP: server rejected the bridge (code {code}) {n} times — giving up. Fix: sign out and sign in again from the account view; if it still fails, send Prism Support the diagnostic from this panel."

Connection dropped

You see: "Connection dropped — retrying…"

Meaning. The connection to Prism dropped. Prism reconnects on its own. Work already sent to After Effects may still finish.

Fix. Wait 10 seconds, then check recent results. Do not run it again.

sleep, a VPN reconnected, or the network changed. It is the most common disconnect we record and not a fault in Prism or After Effects.

allow live.oneprism.io.

Shows in: the panel header. Close codes 1001 (the panel closed or After Effects quit) and 1000 (a clean close) are normal.

Timeouts: do not re-run

Every entry here means the transport gave up waiting and After Effects did not. Re-running a timed-out call duplicates layers, keyframes and imports; collect the late result with a check of recent results instead.

Still running

You see: "After Effects did not respond within {N}s, but the script is almost certainly STILL RUNNING or already COMPLETED in the panel. Do NOT re-run it…"

Meaning. After Effects has not answered after N seconds. The scene build is probably still running or already done.

Fix. Wait, then check recent results. Do not run it again; that duplicates the work.

for it) and stopped waiting; the script kept going in After Effects.

requestId, and _context says whether After Effects is still working. 3. Or do a scoped read, after_effects with comp:"Name", and check what landed. 4. For long work, pass timeout in milliseconds (up to 120000) on the call, and chunk frame loops to about 20 frames per call. Most AI clients abort at 60 seconds, so about 55 is the practical ceiling.

instead of resending.

Shows in: your AI client.

A newer wording of the same message reads "…a timeout here is the transport giving up, not After Effects. Do NOT re-run this call…". Same meaning, same fix. Scene builds say "The scene build did not respond within {s}s…": do not resend the scene; check recent results or snapshot the comp.

Connection dropped

You see: "The bridge to After Effects dropped while this call was in flight. The script may still be running or already completed in AE — do NOT re-run it…"

Meaning. The connection to Prism dropped. Prism reconnects on its own. Work already sent to After Effects may still finish.

Fix. Wait 10 seconds, then check recent results. Do not run it again.

1006 drop, while After Effects had the script.

Shows in: your AI client. The panel log reads "MCP: bridge down — result buffered…" and then "MCP: re-sent {n} buffered result(s) after reconnect."

After Effects busy · panel-busy

You see: "After Effects appears BUSY: {N} earlier call(s) may still be executing and the panel's connection is down (a long script blocks the panel's heartbeat — busy, not gone). THIS call was not run at all…"

Meaning. After Effects is still running earlier work, so this call was not run. The panel reconnects on its own.

Fix. Wait 30 seconds, then check recent results. Do not run it again.

heartbeat; the server treats it as busy rather than gone, and this new call was never started.

Shows in: your AI client.

Results not returned · host-result-lost

You see: "After Effects ran Prism's script, but the result did not come back to the panel on this machine. Do not reinstall, the installation is fine…"

Meaning. After Effects ran the work, but its result did not come back. The project may have changed.

Fix. Quit and reopen After Effects. Do not reinstall; the install is fine.

machine.

Shows in: both. A Windows fault fixed in panel 1.4, not recorded since 9 September 2026; the other host states are on Install errors.

Sessions and limits

Session ended · -32001

You see: "Session not found — please re-initialize."

Meaning. This session ended after two hours idle. Nothing ran.

Fix. Reconnect Prism in your AI client.

no longer knows it. The failed call never reached After Effects.

or when you re-select the connector. 2. Re-send the call. Nothing ran the first time, so there is nothing to undo.

Shows in: your AI client, as JSON-RPC error -32001.

Session from another account · session-owner-mismatch

You see: "This mcp-session-id was opened by a different Prism account."

Meaning. This session was opened by a different Prism account. Nothing ran.

Fix. Reconnect Prism in your AI client.

after switching accounts in the same client.

a session id is never shared between accounts.

Shows in: your AI client (HTTP 403).

Too many requests · rate-limited

You see: "Too many /mcp requests — the limit is 600 per 60s per Prism account."

Meaning. Prism received over 600 requests from this account in one minute. Nothing ran.

Fix. Wait 60 seconds, then try again.

and separate from your monthly allowance.

batch_call instead of N calls.

Shows in: your AI client (HTTP 429, with RateLimit headers).

Request too large · payload-too-large

You see: "Request body too large ({n} bytes; the limit for this endpoint is {limit})."

Meaning. The request is larger than Prism accepts. Nothing ran.

Fix. Send the work in smaller pieces.

/tools endpoints and reference it by path.

Shows in: both (HTTP 413).

More than one After Effects

Prism routes a call to a panel by account and device, never by guessing. Two panels on one account are both valid, so Prism asks you to choose.

Several panels signed in · multiple-panels-connected

You see: "{n} copies of After Effects are signed in to this Prism account, so Prism will not guess which one you meant. Nothing was run."

Meaning. N copies of After Effects are signed in to this account, so Prism will not guess. Nothing ran.

Fix. Quit the After Effects you are not using, or name the one you mean.

under your account.

Shows in: your AI client.

Device not found · unknown-device

You see: "No connected After Effects matches device "{id}". Nothing was run."

Meaning. No signed-in After Effects matches the device named. Nothing ran.

Fix. Choose one of the connected devices, or leave the choice empty.

Shows in: your AI client.

When After Effects is there but will not run scripts

These codes mean the bridge is fine and After Effects itself is not running Prism's script. They are install and host problems and live on Install errors and panel states, with the per-user and all-users paths for Mac and Windows.

Two consecutive engine failures raise the banner "After Effects is not responding to Prism. Close any open dialog, check your other monitors, then restart After Effects." Follow it in that order.

Still stuck

Email support@oneprism.io with the panel version (footer, "After Effects MCP v…") and the Copy diagnostic from the panel's Support section. On panel 1.5.1 the Support section may be empty; the version plus the error text is enough.

Connection states that are not errors

These appear in the panel header or log while nothing is wrong. Listed so a pasted line finds its meaning.

Connecting to Prism

You see: "Connecting… (Connecting to Prism…)…"

Meaning. Prism is connecting.

Fix. Wait a few seconds.

Waiting for sign in

You see: "[WARN] MCP: no valid Prism session token yet — retrying in {…"

Meaning. Prism is waiting for your sign in before it connects.

Fix. Sign in from the panel.

Renewing sign in

You see: "[WARN] MCP: server closed the bridge (code {code}) — renewin…"

Meaning. Prism's sign in was refused once. It is renewing the sign in and reconnecting.

Fix. Wait a few seconds.

Connection failed

You see: "Retry (Could not reach {host} — click to retry) · [WARN] MCP: still disconnected after {n} attempts — retrying…"

Meaning. Prism cannot reach its server after several attempts. It keeps retrying every 30 seconds.

Fix. Check your internet, then click Retry.

Common questions

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