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Error 131026
131026Message Undeliverable
Recipient issue:This is a problem on the recipient's side.
What this error means
This is a broad error indicating WhatsApp was unable to deliver your message. It can stem from multiple recipient-side issues: the phone number may not be registered on WhatsApp, the user may not have accepted the latest Terms of Service, or their app version may be too old to receive certain message types.
Common causes
- •The recipient phone number is not registered on WhatsApp.
- •The recipient has not accepted the latest WhatsApp Terms of Service and Privacy Policy.
- •The recipient is using an outdated version of WhatsApp (below Android 2.21.15.15, iOS 2.21.170.4, or KaiOS 2.2130.10).
- •You sent an authentication template to a user in India (not supported).
- •Marketing frequency capping applied to this recipient.
How to fix
- Verify the number is registered on WhatsApp before sending (use the WhatsApp phone number lookup API if available).
- Ask the recipient to open WhatsApp > Settings > Help and accept the latest Terms of Service.
- Ask the recipient to update their WhatsApp application to the latest version.
- Try sending a simple utility message first to test reachability.
- If the number repeatedly fails, filter it out from future campaigns.
When this cannot be fixed
If the number is simply not on WhatsApp or the user refuses to update, there is no way to deliver the message. Consider reaching them through SMS, email, or other channels.