RocketChat/Rocket.Chat · error · Error

Param must be an array

Error message

Param ${params.teams.key} must be an array

What it means

Validation error from POST channels.create: the optional teams parameter was provided but is not an array. teams must be an array of team identifiers to add the new channel to; a single team ID string or an object fails this check (unlike the other messages, this one interpolates the key without quotes).

Solutions

1. Wrap team IDs in an array: teams: ["teamId123"]
2. Prefer the dedicated teamId parameter when creating a channel inside one team via the teams API semantics — check the endpoint docs for which is expected
3. Omit teams when the channel should not belong to any team

Example fix

// before
{ "name": "dev-talk", "teams": "teamId123" }

// after
{ "name": "dev-talk", "teams": ["teamId123"] }

if (body.teams !== undefined && !Array.isArray(body.teams)) {
  body.teams = [String(body.teams)];
}

const isTeamsArray = (t: unknown): t is string[] =>
  t === undefined || Array.isArray(t);

try { await POST('/api/v1/channels.create', body); } catch (e) {
  if (/teams.*must be an array/.test(e.message)) { /* wrap single ID in array, retry */ }
}

When it happens

Trigger: POST /api/v1/channels.create with teams: "teamId123" instead of teams: ["teamId123"], or teams: {teamId: true} from a checkbox-style form payload.

Common situations: Adding a channel to exactly one team and skipping the array wrapper; client serializers collapsing single-element arrays; confusing the teams array-of-IDs with the teamId single-ID parameter used for creating inside a team.

Related errors

• Param " " must be an object if provided
• Param " " must be an array if provided
• Param " " is required
• error-not-allowed
• error-room-archived

AI-assisted analysis of RocketChat/Rocket.Chat@e4b8178b20 (2026-08-18). Data as JSON: /api/errors/2fd773dcd00a9dce. Report an issue: GitHub.

Appendix: source

Thrown at apps/meteor/server/api/v1/channels.ts:1031

		(teamId && team && !(await hasPermissionAsync(params.user.value, 'create-team-channel', team.roomId)))
	) {
		throw new Error('unauthorized');
	}

	if (!params.name?.value) {
		throw new Error(`Param "${params.name?.key}" is required`);
	}

	if (params.members?.value && !Array.isArray(params.members.value)) {
		throw new Error(`Param "${params.members.key}" must be an array if provided`);
	}

	if (params.customFields?.value && !(typeof params.customFields.value === 'object')) {
		throw new Error(`Param "${params.customFields.key}" must be an object if provided`);
	}

	if (params.teams?.value && !Array.isArray(params.teams.value)) {
		throw new Error(`Param ${params.teams.key} must be an array`);
	}
}

async function createChannel(
	userId: string,
	params: {
		name?: string;
		members?: string[];
		customFields?: Record<string, any>;
		extraData?: Record<string, any>;
		readOnly?: boolean;
		excludeSelf?: boolean;
	},
): Promise<{ channel: IRoom }> {
	const readOnly = typeof params.readOnly !== 'undefined' ? params.readOnly : false;
	const id = await createChannelMethod(
		userId,
		params.name || '',

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