Manychat + n8n for IG Direct: an old reply is sent before the webhook finishes

Question

Hello everyone!I’m building an Instagram Direct agent: ManyChat (Instagram Direct Messages) → External Request → n8n → reply to the user. What’s happening (the issue) 	A user messages us in IG DM.			ManyChat triggers an External Request (webhook to n8n) and immediately sends a message to the user, but it’s an old value (looks like it’s pulled from a custom field from a previous run).			A few seconds later, n8n finishes processing and produces a new reply (I can see the correct text in the output of the last n8n node).			But the user doesn’t receive anything else — they only get the early “old” message that was sent before the webhook completed.	 How can I force ManyChat to wait for the webhook response (External Request) so the Send Message uses the updated value? Is there a reliable way to make the flow pause “synchronously” between External Request and the following blocks?

Fabio Gaulke · Accepted Answer

Hi, ​@Fabio Gaulke!Thank you for your suggestion. I done what you suggested, but it still works wrong. The same problem. N8N complete in 30-50 seconds.What is my mistake?I attached my automation.If n8n takes more than 10sec, the only way is to do it in an asynchronous way…in other words, the automation end once it sends the request, n8n processes it and after 30-50 seconds, it uses Manychat API to set the response in a custom field and starts an automation just to deliver the answer.In this example I'm using a message trigger and a Data Collection block, but you're using the Default Reply trigger, this means you just need the trigger and the Action + External RequestIn the request, you can simply insert the Full Contact Data and send it to n8n or build yout JSON with just the fields you wish:PS: you must also send the subscriber ID to be able to set the response field and start the second automation.NOTHING will be set in response mapping.Now, the second automation can be as simple as this:No trigger, just a message step with the custom user field you use to store the LLM Response.In n8n:This is my test automation.Web hook receives the information from ManychatEdit Fields (var) isolates the subscriber_id and last_input_textLLM Chain does a test prompt (mine is to translate the incoming text to gerrman 😅)Wait node to be sure it will take more than 10sec to processHTTP Request setCustomField =https://api.manychat.com/swagger#/Subscriber/81138a426b0903687848fdf8bdde6aa9HTTP Request sendFlow =https://api.manychat.com/swagger#/Sending/28f1abbb07b0d4773b846dbeb3880e3cINFO:To get the custom field id you just need to go to Settings/ Fields and hover your field to see it's idAnd the flow_ns code you find in the URL when editing the automation:https://app.manychat.com/fb123456/cms/files/18996983--31398422--content20250917002309_255153/edit(content20250917002309_255153 in this example)In this way, you will have one automation that justsends requests to n8nn8 will process it and can take as long as neededOnce it finishet, via Manychat API you will:insert the response in the users custom fielscall the automation that sends the response to the userThis should do the trick. 😁

Fabio Gaulke · Answer

Hi, ​@lvshts!Just set a Smart Delay step between your External Request and the answer/message with the custom field that receives the response.That should do the trick. 😉It is also important to remember that Manychat has a 10sec timeout for external requests. So keep an eye on yourn8n automation processing time to stay under that time.If it takes more than 10sec to respond, you have to use Manychat's API to set the custom field valueasynchronously and set the smart delay to more time.

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