RocketChat/Rocket.Chat · error · Meteor.Error

error-app-prevented

error-app-prevented

Error message

error.message

What it means

Meteor.Error('error-app-prevented') thrown when an app's IPreRoomUserJoined handler throws an AppsEngineException during addUserToRoom; the app's message becomes the reason. Non-app errors are rethrown as-is.

Source

Thrown at apps/meteor/server/lib/rooms/addUserToRoom.ts:75

	try {
		const inviterUser = inviter && ((await Users.findOneById(inviter._id)) || undefined);
		// Not "duplicated": we're moving away from callbacks so this is a patch function. We should migrate the next one to be a patch or use this same patch, instead of calling both
		await beforeAddUserToRoomPatch([userToBeAdded.username!], room, inviterUser);
		await beforeAddUserToRoom.run({ user: userToBeAdded, inviter: inviterUser }, room);
	} catch (error) {
		throw new Meteor.Error((error as any)?.message);
	}

	// TODO: are we calling this twice?

	await callbacks.run('beforeAddedToRoom', { user: userToBeAdded, inviter });

	try {
		await Apps.self?.triggerEvent(AppEvents.IPreRoomUserJoined, room, userToBeAdded, inviter);
	} catch (error: any) {
		if (error.name === AppsEngineException.name) {
			throw new Meteor.Error('error-app-prevented', error.message);
		}

		throw error;
	}

	// for federation rooms we stop here since everything else will be handled by the federation invite flow
	if (isRoomNativeFederated(room)) {
		return;
	}

	// TODO: are we calling this twice?
	if (room.t === 'c' || room.t === 'p' || room.t === 'l') {
		// Add a new event, with an optional inviter
		await callbacks.run('beforeAddedToRoom', { user: userToBeAdded, inviter }, room);

		// Keep the current event
		await callbacks.run('beforeJoinRoom', userToBeAdded, room);
	}

View on GitHub (pinned to b2c16d5842)

Solutions

1. Read the app-provided message for the veto reason.
2. Adjust the app's rules or configuration for the affected room/user.
3. Disable or update the app if the veto is wrong.

try {
  await addUserToRoom(rid, user, inviter);
} catch (error: any) {
  if (error?.error === 'error-app-prevented') {
    // error.reason is the app's veto message for IPreRoomUserJoined
  }
}

When it happens

Trigger: An installed app vetoes adding a specific user to a room while addUserToRoom processes the membership add.

Common situations: Apps gating joins by approval, reputation, or external policy; app regressions blocking all adds.

Related errors

• error-app-prevented
• error-app-prevented-deleting
• error-app-prevented
• Only channels, private groups and direct messages can be cre
• Invalid user

AI-assisted analysis of RocketChat/Rocket.Chat@b2c16d5842 (2026-08-18). Data as JSON: /api/errors/87be16864067da90. Report an issue: GitHub.