WhatsApp error 131026 (message undeliverable): the causes Meta lists and a diagnosis checklist

WhatsApp error 131026 means WhatsApp could not deliver the message to that phone number. Meta's error reference titles it Message Undeliverable and says reasons can include: the recipient phone number is not a WhatsApp phone number; the recipient has not accepted the new Terms of Service and Privacy Policy; or the recipient is using an old WhatsApp version. Each of these is about the person you are messaging, not about your account. Other recipients in the same send are not affected.

The three causes Meta lists

1. The number is not on WhatsApp

The most common case in Indian contact lists. Landlines, old numbers, numbers typed with a digit missing, and numbers that have since been reassigned by the operator often have no WhatsApp account at all. The Cloud API does not offer a way to check whether a number is on WhatsApp before you send, so the failure is how you find out.

2. The new Terms of Service have not been accepted

WhatsApp occasionally asks users to accept updated terms and privacy policy. Until they do, business messages may not reach them. Meta says the user can find the prompt under Settings > Help or Settings > Application information, which will ask them to accept the latest terms if they have not already.

3. The WhatsApp app is too old

Meta publishes minimum versions. Below these, messages fail with 131026:

These versions date from 2021, so in practice this cause shows up with very old phones that never update, or feature phones.

Meta's wording is "reasons can include", so the list is not presented as complete. Treat these three as the official explanation, and do not assume anything else (for example, that the customer blocked you) from a 131026 alone.

What it looks like in the webhook

131026 normally arrives in the status webhook after the send request was accepted. Illustrative payload:

{
  "statuses": [
    {
      "id": "wamid.HBgMOTE5ODEyMzQ1Njc4FQIAERgSN0Q...",
      "status": "failed",
      "timestamp": "1761822000",
      "recipient_id": "919812345678",
      "errors": [
        {
          "code": 131026,
          "title": "Message Undeliverable",
          "message": "Message Undeliverable",
          "error_data": {
            "details": "Message Undeliverable."
          }
        }
      ]
    }
  ]
}

Note the recipient_id. If the digits there are not the number you meant to message, the problem is your formatting, not the customer's phone.

Diagnosis checklist

Work through these in order. The first two take a minute and solve a surprising share of cases.

1. Check the number format. The to field should be the full international number in digits: country code plus number, for example 919812345678 for an Indian mobile. A leading 0, a missing 91, or an extra digit sends the message to a different number.
2. Check the number is a mobile. Landline and toll-free numbers imported from a CRM or a lead form usually have no WhatsApp account.
3. Message it from a normal phone. Save the number on your own phone and open WhatsApp. If no profile appears, it is not on WhatsApp.
4. Ask the customer to message you. Meta's first suggestion is to confirm, through a non-WhatsApp channel such as SMS, a call or email, that the person can actually send a message to your business number. If their message reaches you, the number works.
5. Ask them to accept the latest terms. Point them to Settings > Help or Settings > Application information in WhatsApp.
6. Ask them to update WhatsApp from the Play Store or App Store.
7. Retry once, after they confirm. If the person has messaged you, you are inside a customer service window and can reply directly.

Codes that look similar

If you see 130472 or 131049 instead, the number is fine and the reason is about marketing delivery rules.

A worked example

Meera imports 3,200 leads from a property expo into Rangoli Home's CRM and sends a utility template confirming their visit registration. 96 messages fail with 131026 (illustrative). She exports the failures and finds three patterns: 41 numbers start with 0 and were sent as 910...; 22 are Jaipur landlines from the visitor's office; the rest look like valid mobiles.

She fixes the 41 formatting errors and resends. She removes the landlines from WhatsApp lists and keeps them for calls. For the remaining 33, the sales team sends an SMS with a click-to-chat link to the business number. The people who tap it open a conversation themselves, and the team replies inside the window.

Should you keep retrying?

No. Each cause needs the recipient to change something, so automatic retries just add failed sends to your reports. Meta charges only for delivered messages, so the failure costs nothing, but a list full of dead numbers makes campaign numbers harder to read. Mark 131026 contacts, stop sending to them, and lift the mark when they message you. For list hygiene and opt-in habits that reduce this error, read our opt-in best practices.

How Broadchat shows this

When a message fails, Broadchat records Meta's status webhook and shows the reason in plain English: "The number is not on WhatsApp, or cannot receive this message (old app version / not accepted terms)." In the Inbox it appears under the failed message, and Message info shows the code 131026. Campaign reports list failed recipients, which you can export as CSV for cleaning, and campaigns do not retry 131026 automatically. Test messages sent from a channel also wait for Meta's status, so a test to a number that is not on WhatsApp is reported as failed rather than as sent.

More codes and their fixes are in the WhatsApp API error codes cheat-sheet. If you are new to the platform, start with what the WhatsApp Business API is, and see how broadcasts work in Broadchat.