2029: Stickers can only be sent over iMessage

2xxx — Resource Errors

A sticker reaction was sent to a chat that is not on iMessage.

Stickers can only be sent over iMessage. The target message belongs to a chat on SMS or RCS, neither of which supports peeling a sticker onto a message. This is an HTTP 409 error.

Troubleshooting

Send a standard tapback instead — love, like, dislike, laugh, emphasize, or question — which SMS and RCS do support
Check iMessage capability for the recipient before sending a sticker