sveltejs/kit · error · Error

Cannot call a command (${__.name}) ${violation}

Error message

Cannot call a command (${__.name}) ${violation}

What it means

Runtime guard around a remote command invocation: commands are mutative and may only run inside a mutative request (POST/PUT/PATCH/DELETE). The wrapper rejects the call when the request method is non-mutative, or when the call happens inside a remote query/prerender function (which must stay pure). The message states which violation occurred — wrong HTTP method handler or nested in query/prerender.

Source

Thrown at packages/kit/src/runtime/app/server/remote/command.js:78

	/** @type {RemoteCommandInternals} */
	const __ = { type: 'command', id: '', name: '' };

	/** @type {RemoteCommand<Input, Output> & { __: RemoteCommandInternals }} */
	const wrapper = (arg) => {
		const { event, state } = get_request_store();

		if (
			!MUTATIVE_METHODS.includes(event.request.method) ||
			state.is_in_remote_query ||
			state.is_in_remote_prerender
		) {
			const violation =
				state.is_in_remote_query || state.is_in_remote_prerender
					? `inside a query or prerender function`
					: `from a ${event.request.method} handler`;

			throw new Error(`Cannot call a command (${__.name}) ${violation}`);
		}

		if (state.is_in_render) {
			throw new Error(`Cannot call a command (${__.name}) during server-side rendering`);
		}

		const promise = Promise.resolve(
			run_remote_function(event, state, true, () => validate(arg), fn)
		);

		// @ts-expect-error
		promise.updates = () => {
			throw new Error(`Cannot call '${__.name}(...).updates(...)' on the server`);
		};

		return /** @type {ReturnType<RemoteCommand<Input, Output>>} */ (promise);
	};

View on GitHub (pinned to 03f1687fe6)

Solutions

1. Call the command from a POST/PUT/PATCH/DELETE handler or a form submission, not from a GET
2. Move the mutation out of the query/prerender function and into a command invoked by user interaction

When it happens

Trigger: Thrown at packages/kit/src/runtime/app/server/remote/command.js:78 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/1b17ee0578e8da22. Report an issue: GitHub.