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Connection problems

ChatSyncs itself rejected the key: it’s mistyped, or it was regenerated after you copied it.Open the API Developer Console and copy the key again, without a space at either end (the most common cause). If you regenerated the key recently, every older connection needs the new one.
In Claude, this means the connector was added with Use Claude’s published identity, which ChatSyncs doesn’t support. Remove the connector and add it again, choosing Register automatically. See Claude.In any app, it can also mean the app’s registration is out of date: remove ChatSyncs from the app and add it again.
The app asked ChatSyncs to send you back to an address it didn’t register, so ChatSyncs stopped, to protect your key. Remove ChatSyncs from the app and add it again. If it keeps happening, update the app.
The connect page is valid for 10 minutes. Start the connection again from your app and paste your key within that time.
Until 5 October 2026 ChatSyncs refused sign-in addresses that start with an app’s own name, such as Cursor’s cursor://, so Cursor couldn’t connect. That is fixed. Switch ChatSyncs off and on in the app (or restart it) and sign in again.If it still fails, the app is asking to be sent back to a plain http:// address on another computer, which ChatSyncs refuses because it would expose the sign-in. Connect with your API key in a header instead. See Cursor.
Desktop apps such as Cursor get the result through your browser. The browser asks something like “Open Cursor?”: choose Open. If you missed it, click Continue on the ChatSyncs page, or start the sign-in again from the app.
ChatSyncs sends this detail since 5 October 2026: run /mcp auth chatsyncs again. If it still appears, connect with your API key in a header, as shown on the Gemini CLI page.
Connections made before 5 October 2026 may not renew themselves in ChatGPT. Open ChatSyncs on chatgpt.com/plugins, reconnect, and paste your key once more. New connections keep renewing.
Check the server address is exactly https://mcp.chatsyncs.com/mcp, with no typo and nothing added (not /sse). In apps that ask for a transport, choose HTTP or “Streamable HTTP”: ChatSyncs doesn’t support SSE. Then remove ChatSyncs and add it again.
The connection is switched off for this chat. Turn it on:
  • Claude: + → Connectors → switch on ChatSyncs.
  • ChatGPT: type @ChatSyncs in the message where you want it.
  • VS Code: Configure Tools in the chat box; make sure the server is started.
  • Cursor: Customize → check the chatsyncs toggle is on.
  • Claude Code, Codex, Gemini CLI: type /mcp to see whether it’s connected.
If that doesn’t help, restart the app.
The key your app holds no longer works. Two usual causes:
  • The key was regenerated. Apps don’t ask for the new key by themselves: reconnect each one. See After you regenerate the key.
  • You connected with the key in a header or in the address (/mcp/k/…) and it’s mistyped. These methods don’t check the key when you connect, only on the first action. Put in the current key, or switch to browser sign-in, which checks it straight away.
Your app’s sign-in ran out, usually because the app went unused for over a year, or you removed and re-added ChatSyncs. Paste the current key and it reconnects.

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Messages not sending

WhatsApp only allows free-form messages within 24 hours of the customer last messaging you. After that, only an approved template is delivered.Ask the assistant to send a template instead: “Send them the re-engagement template.” If you don’t have one, create it in ChatSyncs — see Creating a WhatsApp message template.
Your plan’s contact limit is full, and messaging a new number would create a new contact. Remove contacts you no longer need, or upgrade your plan.
The template needs something the assistant can’t supply: an image, video or document header, a carousel, or variables that aren’t mapped in ChatSyncs. Send that template from ChatSyncs itself. Plain text templates, with or without variables, work from the assistant; it asks you for any value it can’t fill in.
Ask “check the delivery status of that message.” A message can be accepted by WhatsApp and still fail to deliver — a blocked number, an invalid number, or a phone that’s been offline. Also confirm the number included the country code.

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Wrong number or wrong account

With several connected numbers, say which you mean: “send it from the support number.” To see them all, ask “show me my account.”
The API key is valid but no number is connected to that ChatSyncs account. Follow Connect your number to ChatSyncs.
Your account has several and the assistant won’t guess. Name the number once and it will use it for the rest of the conversation.

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Frequently asked

There’s no bulk-send ability, on purpose — see the tool reference. Use Broadcasting.
That’s your AI app’s own safety behaviour, not ChatSyncs’. Most apps let you approve a tool for the rest of a conversation, or set read-only abilities to run without asking. Keep approval on for anything that sends messages.

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Still stuck

Tell support:
  1. What you asked the assistant to do
  2. The exact error text it showed you
  3. Which app you’re using (for example claude.ai, ChatGPT, Cursor, Claude Code) and how you connected it (browser sign-in, header, or key in the address)
Never include your API key in a support message, a screenshot or a bug report. If you think it’s been exposed, regenerate it immediately on the API Developer Console.