WhatsApp reminder not delivered from n8n: the 24-hour window

Test record: run by Fractional HQ on 11 November 2026 on n8n 2.23.4, with Meta's WhatsApp test number and a real phone as the customer. Runs 94136 and 94159 sent reminders inside the 24-hour window, as replays of a real message. Not tested: a reminder outside the window, n8n Cloud, a live business number, the approved-template version.

Symptom

We have not watched one of these fail. On 11 November 2026 we ran our WhatsApp booking template by hand on n8n 2.23.4, with a real phone as the customer and Meta's WhatsApp test number as the sender. The reminder in that template is a plain text message. Two reminders went out on the first version of the file, in runs 94136 and 94159, both under an hour after our last message from the phone, so both were inside the window.

While we were writing up the run we noticed that our setup guide did not mention the rule at all.

Why it happens

Meta sorts WhatsApp Business messages into two kinds. A free-form message, which is what a plain text from the WhatsApp node is, can only be sent while a customer service window is open, and that window lasts 24 hours from the customer's last message. Outside the window, Meta only delivers a message built from a template that it has approved in advance. This is Meta's rule for the Cloud API as we understand it, and nothing in n8n changes it.

A booking flow runs into this almost by design, because the customer writes once to book and then goes quiet until the day of the appointment.

The fix

There are two ways round it, and we have only used the first.

The first is to keep the plain text and accept that it only reaches customers who wrote within the last day. The template ships with reminders switched off and a lead time of 60 minutes, and the guide in the pack sold here now explains the 24-hour rule.

The second is to send the reminder as an approved template message. You create the template in WhatsApp Manager, wait for Meta to approve it, and change the reminder node from a text send to a template send. The guide tells the buyer to make that change before relying on reminders for bookings made more than a day ahead. We have not built or run that version, so we cannot tell you how long approval takes or what the node needs.

How we found it

The run is in our log by execution number. Run 94136 booked a 17:00 appointment with reminders switched on, the wait woke at 12:35, the booking was still current, and the reminder was sent and accepted by Meta. Two other reminder runs were held back as they should have been, one because staff had taken over the chat and one because the booking had been cancelled. All of these were replays, which means runs we started from a real message sent from a phone, with the text changed.

What we did not establish

We did not send a reminder outside the 24-hour window, so we have not seen the error Meta returns or whether the WhatsApp node reports it as a failure. We did not test on n8n Cloud. We used Meta's test number throughout, and we did not check whether a live business number behaves differently.

Written by Fractional HQ from its own runs. If your n8n behaves differently, email hello@fractionalhq.uk and we will correct the note.