Facebook Messenger Send API error codes, explained one by one

In the HTTP response body of the Send API call that failed, as an error object with code, error_subcode, message, type and fbtrace_id. Messenger does not report send failures through a separate webhook the way WhatsApp does, so if the call returned a message_id the platform accepted it. Log the whole error object on every non-200 response; a bot that discards it has no other record of the failure.

Your app is in Development mode, or it is Live with only Standard Access to pages_messaging. Either way the Send API returns code 200: it can only message people with a role on the app until pages_messaging passes App Review and the app is Live with Advanced Access. Request the permission in the App Dashboard and submit a screencast of the bot flow for review.

Once a person messages your Page, clicks Get Started, or comments on your post, you have 24 hours to reply with anything, including promotional content. After that, sends fail with code 10 and subcodes such as 2018278 or 2534022. Outside the window your options are the HUMAN_AGENT tag (7 days, App Review required), one-time notifications, sponsored messages, or waiting for the person to message again.

Effective April 27, 2026, API requests using CONFIRMED_EVENT_UPDATE, ACCOUNT_UPDATE or POST_PURCHASE_UPDATE receive error code 100. HUMAN_AGENT remains: it lets a human respond within 7 days of the person's last message, but only after the app is approved for the Human Agent permission through App Review. CUSTOMER_FEEDBACK remains documented for the Customer Feedback Template within 7 days. Marketing content is never allowed under any tag.

The person has blocked your Page or messages from it, deactivated or deleted their Facebook account, or restricted who can message them. It is not a bug and there is no workaround or way to check in advance. Treat 551, and its neighbours 200 subcode 1545041 and 10 subcode 2018108, as a permanent opt-out for that PSID: mark the contact unreachable and stop retrying.

Messenger recipient IDs are Page-scoped (PSIDs): the same person has a different ID for every Page and for every app-Page pair. IDs saved from another Page, another app, or from Facebook Login (app-scoped IDs) will not resolve, and the API answers code 100 subcode 2018001. Only use PSIDs from your own webhook events for the same Page, and re-key contacts after migrating apps.

Retry 1200 (temporary send failure), 1 and 2 (platform trouble) with exponential backoff. Back off and slow down on the throttling codes 4, 17, 32, 613 and 80006, since more calls extend the block. Never retry permanent errors: 551 and 100/2018001 (unreachable or wrong recipient), 10 window errors before the person replies again, or 190 until the token is replaced.

The documented ceiling is 200 API calls per 24 hours multiplied by the Page's engaged users, with the Send API further capped at 300 calls per second per Page for text and 10 per second for audio or video. Crossing them returns codes 4, 17, 32, 613 or 80006. The full table, including profile and menu API limits, is in the Messenger limits reference at /limits/messenger.

Invalid OAuth access token: the Page access token has expired, was invalidated by a password change or permission revoke, or was pasted incorrectly. The bot's webhook usually still fires, but every reply fails until you generate a new token. Inspect the token in Meta's Access Token Debugger, generate a long-lived Page token, and update the credential your server sends.

fbtrace_id is an internal trace identifier attached to every Graph API error. Meta engineers use it to find the server-side logs for your exact failed request, and Developer Support will ask for it, so persist it with the code, subcode and timestamp. It expires after a short period, which is one more reason to file bug reports promptly with a recent trace attached.