What causes "Invalid command parameter provided, must be a string." in RocketChat/Rocket.Chat?

Pass a concrete, non-empty command string.

RocketChat/Rocket.Chat · error · Error

Invalid command parameter provided, must be a string.

Error message

Invalid command parameter provided, must be a string.

What it means

`AppCommandsBridge.enableCommand(command, appId)` (commands.ts:31-36) re-enables a previously disabled slash command. Its first guard rejects a `command` that is not a non-empty trimmed string. enableCommand is reached via the apps-engine command-modifier accessor; passing anything but a real command name aborts here before any state lookup.

Source

Thrown at apps/meteor/app/apps/server/bridges/commands.ts:35

	}

	protected async doesCommandExist(command: string, appId: string): Promise<boolean> {
		this.orch.debugLog(`The App ${appId} is checking if "${command}" command exists.`);

		if (typeof command !== 'string' || command.length === 0) {
			return false;
		}

		const cmd = command.toLowerCase();

		return typeof slashCommands.commands[cmd] === 'object' || this.disabledCommands.has(cmd);
	}

	protected async enableCommand(command: string, appId: string): Promise<void> {
		this.orch.debugLog(`The App ${appId} is attempting to enable the command: "${command}"`);

		if (typeof command !== 'string' || command.trim().length === 0) {
			throw new Error('Invalid command parameter provided, must be a string.');
		}

		const cmd = command.toLowerCase();
		if (!this.disabledCommands.has(cmd)) {
			throw new Error(`The command is not currently disabled: "${cmd}"`);
		}

		slashCommands.commands[cmd] = this.disabledCommands.get(cmd) as (typeof slashCommands.commands)[string];
		this.disabledCommands.delete(cmd);

		void this.orch.getNotifier().commandUpdated(cmd);
	}

	protected async disableCommand(command: string, appId: string): Promise<void> {
		this.orch.debugLog(`The App ${appId} is attempting to disable the command: "${command}"`);

		if (typeof command !== 'string' || command.trim().length === 0) {
			throw new Error('Invalid command parameter provided, must be a string.');

View on GitHub (pinned to f9d3ec372b)

Solutions

Pass a concrete, non-empty command string.
Guard with `typeof command === 'string' && command.trim().length > 0` before calling enable.
Confirm the command was previously disabled (see error 3) in the same process.

Example fix

// before
modifier.enableCommand(name) // name is undefined
// after
if (typeof name === 'string' && name.trim()) {
  await modifier.enableCommand(name);
}

Defensive patterns

Strategy: validation

Validate before calling

const cmd = asCommandName(rawValue);
if (cmd) {
  await modifier.enableCommand(cmd);
}

Type guard

const isCommandName = (v: unknown): v is string => typeof v === 'string' && v.trim().length > 0;

function asCommandName(v: unknown): string | null {
  return isCommandName(v) ? v : null;
}

Prevention

Normalize command names to non-empty strings at the boundary of your app.
Avoid passing values read from settings/storage without a type check.
Centralize command lifecycle calls behind a helper that validates the name.

When it happens

Trigger: Calling the command modifier's enable with undefined, a number, an object, or a whitespace-only string — e.g. `getSlashCommandModifier().enableCommand(nameFromConfig)` where nameFromConfig is undefined.

Common situations: App reads the command name from settings/storage that is unset; a programmatic command lookup returned undefined and was passed through; refactor changed the variable type.

Related errors

AI-assisted analysis of RocketChat/Rocket.Chat@f9d3ec372b (2026-08-12). Data as JSON: /api/errors/2c8337b54b22a69f. Report an issue: GitHub.