WhatsApp error 131051: Unsupported message type

Code 131051 means the type you sent, or the shape of the object that goes with it, is not something the Cloud API will accept on this endpoint. The supported top-level types are a fixed list (text, image, audio, video, document, sticker, location, contacts, interactive, template, reaction, and a few others) and the platform rejects anything else outright. It also appears when a media message references a file whose MIME type is outside the supported set, because the platform cannot classify it as any deliverable type.

Most hits come from three places: a typo or casing mismatch in the type string, a value borrowed from another messaging platform (for example, file or photo), and media uploaded with a correct-sounding extension but an unsupported actual format such as a GIF, HEIC, or an MKV container.

The recipient, window, and token are irrelevant here; the request itself is not a message WhatsApp can send.

The rejection is synchronous - the type check runs before the message is accepted, so no message ID is issued and no statuses webhook follows. The full matrix of supported formats and size ceilings per media type is tabulated in the WhatsApp media limits table. Distinguish it from 131053, where the type is fine but the platform could not fetch or process the file, and from code 100, which flags unknown keys rather than unknown types. One gotcha for teams on multi-channel abstractions: if your BSP or messaging layer normalizes payloads across channels, a message type that is legal on another channel (a GIF, a generic file attachment) can reach WhatsApp as unsupported, so check the WhatsApp-specific mapping in your provider's documentation rather than the generic one.

{
  "error": {
    "message": "(#131051) Unsupported message type",
    "type": "OAuthException",
    "code": 131051,
    "error_data": {
      "messaging_product": "whatsapp",
      "details": "Message type is not currently supported"
    },
    "fbtrace_id": "AzXcVbNm12QwEr"
  }
}

Whitelist message types and MIME types in your sending code and reject anything else before it reaches the API, with a conversion step for common unsupported formats. Sniff MIME types from content, never from extensions, and include the supported media matrix in the tests you run against each message type.