Discord error 10062: Unknown interaction

You tried to respond to an interaction (slash command, button, select menu, modal) that Discord no longer recognizes. The overwhelming cause is timing. When a user triggers an interaction, Discord hands you a token and expects an initial response within 3 seconds. If nothing arrives in that window the interaction is discarded, and any later attempt to reply with that token returns 10062.

The 3 seconds start when Discord creates the interaction, not when your code receives it. Network latency, a slow event loop, a cold-started serverless function, or a synchronous database call before the reply all eat into the budget. Bots that work fine on a laptop and fail in production are usually losing the extra few hundred milliseconds of hosting latency.

The fix is not to be faster; it is to acknowledge first. Sending a deferred response (type 5, DEFERRED_CHANNEL_MESSAGE_WITH_SOURCE, or type 6 for component updates) counts as the initial response. The user sees a "thinking" state and you then have 15 minutes to edit the reply via the interaction webhook.

The pattern is two lines in any maintained library, with the acknowledgement before every piece of I/O:

// discord.js - ack within 3 seconds, then take up to 15 minutes
await interaction.deferReply();
const answer = await doSlowWork();
await interaction.editReply(answer);

# discord.py - same shape
await interaction.response.defer()
answer = await do_slow_work()
await interaction.edit_original_response(content=answer)

Note what the defer buys you: the interaction token stays usable for 15 minutes for editing the original response and posting follow-ups through the webhook routes. It does not remove the 3-second deadline; it satisfies it. If even the defer arrives late, because the process was cold-starting or the event loop was blocked, you still get 10062, which is why the defer must be the first awaited call in the handler rather than merely an early one.

{
  "message": "Unknown interaction",
  "code": 10062
}

Adopt defer-then-edit as the default shape for every command handler that does anything beyond returning a constant string. Keep the code path between receiving the event and sending the ack free of I/O. If you run the bot serverless, keep a warm instance or move interaction handling to a long-lived process.

The 3-second and 15-minute windows are listed with sources on the Discord limits page, and the "application did not respond" section of Discord bot not responding walks the same fix through a full bot.