Messenger error 10: User stopped notification messages for this topic

Code 10 with subcode 1893015 belongs to Messenger's marketing-messages (recurring notifications) system. Meta's error-codes table states the trigger exactly: it fires "when the Page sends a Marketing Message after the user clicks 'Stop these messages'." The person opted in to a notification topic at some point, later used the in-conversation control to stop them, and your Page kept sending to the topic anyway.

This is an opt-out, not an outage. The opt-in token for that (user, topic) pair is dead, and every further send against it will return the same error. Unlike the silent unreachable states (551, 10/2018108), this one is scoped: the person may still happily chat with your bot and even remain subscribed to a different notification topic; only this topic's permission is revoked.

The compliance angle matters. "Stop these messages" is a consent withdrawal, and continuing to fire sends at a withdrawn consent, even though Meta blocks them for you, is the pattern that feeds Page-level enforcement: the opt-in-request restrictions of 10/1404170 and ultimately policy blocks like 368. Your opt-out bookkeeping should be the thing that prevents the send, with Meta's error as the backstop, not the mechanism.

{
  "error": {
    "message": "(#10) This user has currently stopped notification messages for this topic",
    "type": "OAuthException",
    "code": 10,
    "error_subcode": 1893015,
    "fbtrace_id": "BLBz/WZt8dN"
  }
}

Treat consent as a first-class table with topic granularity and event-driven updates, and make every campaign query join against it. Keep opt-out friction at zero and cadence honest, the recipients who cannot stop messages politely stop them with blocks instead. The marketing-messages caps and their sibling errors are collected in the Messenger limits reference and in the troubleshooting guide.