What causes "User is not in this room" in RocketChat/Rocket.Chat?

Verify current membership (channels.members / groups.members / im.members) before banning

User is not in this room

Error message

User is not in this room

What it means

The target user exists but has no subscription document in the room (Subscriptions.findOneByRoomIdAndUserId empty) - they are not a member, so there is nothing to ban. A banned user keeps a subscription with status 'BANNED', so this error means 'never joined or already fully removed', not 'already banned'.

Source

Thrown at apps/meteor/server/lib/banUserFromRoom.ts:40

	const fromUser = await Users.findOneById(fromId);
	if (!fromUser) {
		throw new Error('Invalid user');
	}

	if (!(await canAccessRoomAsync(room, fromUser))) {
		throw new Error('The required "roomId" or "roomName" param provided does not match any group');
	}

	const bannedUser = await Users.findOneByUsernameIgnoringCase(data.username);
	if (!bannedUser) {
		throw new Error('User not found');
	}

	const subscription = await Subscriptions.findOneByRoomIdAndUserId(data.rid, bannedUser._id, {
		projection: { _id: 1, status: 1 },
	});
	if (!subscription) {
		throw new Error('User is not in this room');
	}

	// Cannot ban a user who is already banned
	if (isBannedSubscription(subscription)) {
		throw new Error('User is already banned from this room');
	}

	// Cannot ban the last owner
	if (await hasRoleAsync(bannedUser._id, 'owner', room._id)) {
		const numOwners = await Roles.countUsersInRole('owner', room._id);

		if (numOwners === 1) {
			throw new Error('You are the last owner. Please set new owner before banning the user.');
		}
	}

	await banUserFromRoom(data.rid, bannedUser, fromUser);

View on GitHub (pinned to b2c16d5842)

Solutions

Verify current membership (channels.members / groups.members / im.members) before banning
Refresh member data before performing the action
For private rooms note that non-members cannot rejoin without an invite, so a ban may be unnecessary

Defensive patterns

Strategy: validation

Validate before calling

const { members } = await GET '/api/v1/channels.members' { roomId }; // or groups.members / im.members
if (!members.some((m) => m.username === username)) {
  // target is not in the room - nothing to ban
}

Try / catch

try {
  await POST '/api/v1/rooms.banUser' { roomId, username };
} catch (e) {
  if (String(e.message).includes('not in this room')) {
    // target left or was removed - no ban needed (distinct from 'already banned')
  } else {
    throw e;
  }
}

Prevention

Verify membership from a live members list before banning
Distinguish 'not in room' from 'already banned' when surfacing UI feedback
For private rooms, non-members cannot rejoin uninvited - a ban is often unnecessary

When it happens

Trigger: Banning a username who left the room; targeting a user who was kicked; pairing a rid with a username taken from a different room.

Common situations: Member lists stale after removals; automations banning from exported member lists; UI member caches out of date.

Related errors

AI-assisted analysis of RocketChat/Rocket.Chat@b2c16d5842 (2026-08-18). Data as JSON: /api/errors/b4862858fdc7ac2c. Report an issue: GitHub.