63021: Channel invalid content error

This error occurs when the content you send does not match the validation rules or supported capabilities of the selected messaging channel. Check the content type, media requirements, and channel-specific component limits before you send the message.

• The message uses a content type or component that the selected channel does not support. Twilio supports different content types across SMS, MMS, RCS, WhatsApp, and Messenger, and not every channel supports every template type.
• The media at MediaUrl is not accepted for the target channel, the Content-Type header does not match the actual file type, or the media exceeds the channel size limit.
• A twilio/quick-reply template exceeds the WhatsApp body limit of 1,024 characters, or the template violates WhatsApp variable rules for approval.
• A button label or card field exceeds the allowed limit for the component you are sending. For example, QUICK_REPLY titles are limited to 20 characters, while URL, PHONE_NUMBER, and VOICE_CALL titles on twilio/card are limited to 25 characters. WhatsApp twilio/card title text is limited to 1,024 characters.

• Confirm that the content type you send is supported on the destination channel. If you send to a mix of channels, add a simpler fallback such as twilio/text so Twilio can deliver a supported translation for each channel.
• Check every media URL before sending. Make sure the file is publicly reachable, the Content-Type header matches the actual file, the MIME type is accepted, and the total media size stays within the channel limit.
• Reduce text and button labels to the documented limits for the template type you are using. For example, keep twilio/quick-reply body text within 1,024 characters, keep twilio/call-to-action body text within 640 characters, and keep button titles within the documented 20-character or 25-character limits.
• For WhatsApp templates that use variables, avoid starting or ending the body with a variable and avoid placing two variables next to each other. Include sample values for variables when approval is required.

• Accepted content types for media
• Content Types Overview
• Using Buttons in WhatsApp