After Effects MCP sign-in errors
Prism signs in twice: once in the panel inside After Effects, once in your AI client, both with the same account. This page covers every code the panel can show, every refusal the server can send, and the client-side mistakes. First, find the code or message you see.
| What you see | Section |
|---|---|
The panel's sign-in box shows a code such as offline or timed-out | Panel sign-in codes |
| Your AI client relays "Sign in to use Prism." or "No Prism plan" | Server refusals |
| The client saved the address but Prism never appears, or asks to sign in again and again | Your AI client |
Panel sign-in codes
The sign-in box shows a message, a fix and a short detail chip, with Try again,
Reinstall or Copy error beside it. The Support log records the same line as
[ERROR] Sign in failed (code) — message Fix: fix. Until the browser answers, the
button reads "Waiting for your browser…".
Prism not reachable
You see: "No connection to Prism."
Meaning. Prism cannot reach its server. Nothing changed.
Fix. Check your internet connection, then sign in again.
Connection blocked
You see: "This machine blocked Prism's connection."
Meaning. Something on this computer is blocking Prism's connection. Nothing changed.
Fix. Allow After Effects through your firewall or antivirus, then sign in again.
Sign in timed out · timed-out
You see: "Sign in timed out after 5 minutes."
Meaning. The browser sign in was not finished within 5 minutes. Nothing changed.
Fix. Sign in again and finish it in the browser within 5 minutes.
Sign in ports busy · port-unavailable
You see: "Sign in ports are busy."
Meaning. Another copy of After Effects is already using Prism's sign-in connection. Nothing changed.
Fix. Quit every other copy of After Effects, then sign in again.
Sign in cancelled
You see: "Sign in cancelled."
Meaning. The sign in was cancelled in the browser. Nothing changed.
Fix. Sign in again when you are ready.
Session expired · session-expired
You see: "Your session expired." and "You are signed out of Prism."
Meaning. Your sign in has expired. Nothing changed.
Fix. Sign in again.
The sign-in wall names one of three reasons: "This sign-in was for a different Prism server." (the saved sign-in was minted for another server, and the panel signs in again by itself), "Your session expired." and "The saved sign-in was refused." (the server refused the renewal three times).
Install cannot sign in · no-node
You see: "After Effects can't run Prism sign in."
Meaning. This install of Prism cannot run sign in. Nothing changed.
Fix. Reinstall Prism from your dashboard, then quit and reopen After Effects.
Sign in unavailable · discovery-failed
You see: "Sign in is unavailable."
Meaning. The sign-in service is not answering. Nothing changed.
Fix. Wait a few minutes, then sign in again. If it persists, email support@oneprism.io.
Sign in not started · registration-failed
You see: "Prism couldn't start sign in."
Meaning. The sign-in service refused to start a sign in. Nothing changed.
Fix. Wait a minute, then sign in again.
Sign in not finished · exchange-failed
You see: "Prism couldn't finish signing you in."
Meaning. The browser accepted your sign in, but Prism could not finish it. Nothing changed.
Fix. Copy the error from the panel and email it to support@oneprism.io.
Server refusals
These reach your AI client as an error, and the panel logs them as
[ERROR] MCP: sign-in refused (code) — message Fix: fix. Every one carries a fix
line, quoted here verbatim.
Not signed in · not-authenticated
You see: "Sign in to use Prism."
Meaning. This AI client is not signed in to Prism. Nothing ran.
Fix. Run the sign-in step in your AI client. If nothing opens, re-add the Prism connector.
Shows in: your AI client.
Not signed in · not-authenticated
You see: "Your Prism session has expired."
Meaning. This AI client is not signed in to Prism. Nothing ran.
Fix. Run the sign-in step in your AI client. If nothing opens, re-add the Prism connector.
Shows in: both.
Not signed in · not-authenticated
You see: "Prism could not verify this session."
Meaning. This AI client is not signed in to Prism. Nothing ran.
Fix. Run the sign-in step in your AI client. If nothing opens, re-add the Prism connector.
Shows in: both.
Sign in service unavailable · auth-unavailable
You see: "Prism could not reach its sign-in service."
Meaning. Prism cannot reach its sign-in service. Nothing ran.
Fix. Wait a moment, then try again. If it persists, email support@oneprism.io.
Do not reinstall the panel or re-add the client entry. Nothing on your side is wrong.
Shows in: both.
No Prism plan · no-prism-plan
You see: "No Prism plan for {email}."
Meaning. This account has no Prism plan. Nothing ran.
Fix. Choose a plan in your dashboard, or sign in with your receipt's email.
Some AI clients answer this refusal by opening the browser again, as if you had never signed in. That loop ends the moment the account has a plan. More on the plan page.
Shows in: both.
Plan not recognised · unknown-tier
You see: "Prism does not recognise the plan "{tier}" on this account."
Meaning. Prism does not recognise the plan on this account. Nothing ran.
Fix. Email support@oneprism.io with your account email.
Shows in: both.
Panel sign in missing · auth-required
You see: "Prism closed this connection because it never received a sign-in frame."
Meaning. The panel connected without signing in, so Prism closed the connection. Nothing ran.
Fix. Update the After Effects MCP panel from your dashboard.
Shows in: the panel log.
Sign in does nothing, wrong account, repeated prompts
Sign in does nothing
What it means. No browser opened, or it opened behind After Effects: no default browser is set, or the window is on another display.
Do this. Check your other windows and monitors, and set a default browser if none is set. After five minutes the panel reports timed-out; Try again from there.
Panel stays signed out
What it means. The browser completed with a different account, or the panel was not reopened. Your dashboard step stays grey while the panel is not connected.
Do this.
- Sign out in the browser.
- Close and reopen the panel.
- Sign in with the email on your dashboard or receipt. A different email creates a separate account, which then fails with "No Prism plan".
Repeated sign-in prompts
What it means. We do not know yet. One customer signed in nine times in three hours, and the cause has not been found. Two cases are explained: the no-prism-plan refusal above is answered the same way as a missing sign-in, so some clients loop until the account has a plan, and the panel signs itself out after three refused renewals.
Do this. Sign in with the same account each time, then email support@oneprism.io with the panel version, which client, and how often it happens.
Your AI client
Approve in the browser
Pasting the address is not enough. The client's sign-in step is what links it to your account, and until it completes every call is refused with "Sign in to use Prism." If the client was already open when you added the address and does not show Prism, quit it and open it again: most clients load their connections at launch.
Streamable HTTP, not STDIO
STDIO launches a program from your own disk. Prism is reached over the network, so STDIO has nothing to launch and the failure looks like Prism is down.
Keeps forgetting the connection
Between 08-05 and 08-15 ChatGPT and Codex could not complete sign-in: the server's
discovery named a different resource from the one those clients asked for, and the
renewal was refused with invalid_target. Fixed on 08-15. Remove and re-add the
Prism entry and sign in again. If you see it today, check the transport and the
browser approval instead.
The right key per client
| Client | Address goes in | Sign-in step |
|---|---|---|
| ChatGPT | Settings, custom MCP server, Streamable HTTP | Authenticate |
| Codex | ~/.codex/config.toml; a project .codex/config.toml is ignored unless trust_level = "trusted" | codex mcp login prism |
| Claude | Custom connector, or claude mcp add --transport http | Approve in the browser, or /mcp |
| Antigravity | serverUrl, never url or httpUrl | First call opens the browser |
| Qwen Code | httpUrl, never url | First call opens the browser |
| Kimi Code | kimi mcp add --transport http --auth oauth | kimi mcp auth prism |
| DeepSeek Harness | An OAuth MCP plugin, not the built-in client | Authorise in the browser |
| Cursor, Windsurf, VS Code and others | url, serverUrl or type http | Approve in the browser |
No client needs an API key or a header. Prism issues no keys, so anything you paste into one is meaningless.
Device not found · unknown-device
You see: "No connected After Effects matches device "{name}". 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.
Other sign-in refusals
Panel sign in invalid · bad-auth-frame
You see: "The first frame was too large to be a sign-in frame. · The first frame was not valid JSON. · The first frame was not a sign-in frame.…"
Meaning. The panel's sign in was not in a form Prism accepts, so Prism closed the connection. Nothing ran.
Fix. Update the After Effects MCP panel from your dashboard.
Device not identified · bad-device-id
You see: "The panel did not present a usable device id.…"
Meaning. The panel did not identify this computer, so Prism closed the connection. Nothing ran.
Fix. Update the After Effects MCP panel, then quit and reopen After Effects.
Common questions
Related
Install
Fix the panel missing from Extensions, a blank panel, and every host state: host-not-loaded, host-not-readable, host-missing, host-stale and install-conflict.
Connection
Fix not-connected, timeout, panel-busy, code 1006 drops, multiple-panels-connected and Session not found: what each means, what to do, and what never to re-run.