remotion-dev/remotion · error · Error

outputLocation must be a string but got ${typeof newOutputLo

Error message

outputLocation must be a string but got ${typeof newOutputLocation} (${JSON.stringify(newOutputLocation)})

What it means

`Config.setOutputLocation()` validates that its argument is a string at runtime; any non-string throws an Error that echoes both the JS type and JSON representation of the value. The setter stores the final output path used by render/still when the user wants to override the CLI-supplied path.

Source

Thrown at packages/cli/src/config/output-location.ts:5

let currentOutputLocation: string | null = null;

export const setOutputLocation = (newOutputLocation: string) => {
	if (typeof newOutputLocation !== 'string') {
		throw new Error(
			`outputLocation must be a string but got ${typeof newOutputLocation} (${JSON.stringify(
				newOutputLocation,
			)})`,
		);
	}

	if (newOutputLocation.trim() === '') {
		throw new Error(`outputLocation must not be an empty string`);
	}

	currentOutputLocation = newOutputLocation;
};

export const getOutputLocation = () => currentOutputLocation;

export const resetOutputLocation = () => {
	currentOutputLocation = null;
};

View on GitHub (pinned to 78fe4bb3fd)

Solutions

Make sure the value is always a string before calling: provide a fallback or assert the env var is set.
Coerce explicitly only if the input truly is string-like: `Config.setOutputLocation(String(value))`.

Example fix

// before
Config.setOutputLocation(process.env.OUT);
// after
Config.setOutputLocation(process.env.OUT ?? 'out/video.mp4');

Defensive patterns

Strategy: type-guard

Validate before calling

const out = process.env.OUT;
if (typeof out !== 'string') {
  throw new Error(`OUT must be a string, got ${typeof out}`);
}
Config.setOutputLocation(out);

Type guard

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

Prevention

Always provide a fallback path when sourcing from env.
Validate at the boundary where untyped data enters the program.

When it happens

Trigger: Calling `Config.setOutputLocation(undefined)`, `Config.setOutputLocation(123)`, `Config.setOutputLocation(null)`, or `Config.setOutputLocation({path: '...'})`.

Common situations: Reading a path from env (`process.env.OUT`) that may be undefined; passing a parsed JSON value that came back as a non-string; programmatically building the path with a helper that can return undefined.

Related errors

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/4db365d827047e92. Report an issue: GitHub.