Discord error 40003: Opening direct messages too fast

You called Create DM (POST /users/@me/channels) too many times in a short window. Discord treats opening DM channels as a spam-sensitive action and applies a dedicated, fairly aggressive limit to it that is separate from the normal route buckets. The docs explicitly warn not to use this endpoint to DM everyone in a server.

Bots that send welcome DMs to every member on a mass join, broadcast an announcement to all members, or re-open a DM channel before every single message (instead of caching the channel ID) are the ones that see this. Note that opening the channel and sending the message are two calls; 40003 comes from the first. Once a DM channel exists you can reuse its ID indefinitely, so the open call should be rare.

{
  "message": "You are opening direct messages too fast.",
  "retry_after": 30.5,
  "global": false,
  "code": 40003
}

Only open a DM in direct response to a user action (they ran a command, clicked a button, joined voluntarily) and persist the channel ID. For announcements, post in a channel and let users subscribe with a role; it scales and does not trigger DM spam protections.

DM-opening pressure almost always signals a broadcast feature that should not exist. Deliver announcements in channels and reserve DMs for user-initiated conversations. The DM-open behavior and its 50007 companion are covered on the Discord limits page, and chatbot API rate limiting covers queueing the sends you keep.