remotion-dev/remotion · error · TypeError

outputRange must contain only numbers, or supported scale, t

Error message

outputRange must contain only numbers, or supported scale, translate, and rotate strings

What it means

Thrown by interpolate() in the mixed string-output branch. When at least one output is a string (hasStringOutput), every output must be either a string or a number — the string-interpolation path supports scale/translate/rotate CSS strings mixed with numbers. If any output is neither (a tuple, boolean, object, null), this TypeError fires before interpolateString is attempted.

Source

Thrown at packages/core/src/interpolate.ts:1185

	if (typeof input !== 'number') {
		throw new TypeError('Cannot interpolate an input which is not a number');
	}

	if (!Array.isArray(outputRange)) {
		throw new Error('outputRange must contain only numbers');
	}

	const hasStringOutput = outputRange.some(
		(output) => typeof output === 'string',
	);
	if (hasStringOutput) {
		if (
			!outputRange.every(
				(output) => typeof output === 'string' || typeof output === 'number',
			)
		) {
			throw new TypeError(
				'outputRange must contain only numbers, or supported scale, translate, and rotate strings',
			);
		}

		try {
			return interpolateString({input, inputRange, outputRange, options});
		} catch (error) {
			if (!outputRange.every((output) => typeof output === 'string')) {
				throw error;
			}

			const hasNonNumericString = outputRange.some((output) => {
				try {
					parseStringInterpolationValue(output);
					return false;
				} catch (parseError) {
					return parseError instanceof UnsupportedStringInterpolationValueError;
				}

View on GitHub (pinned to 78fe4bb3fd)

Solutions

Keep string outputs together only with numbers (no tuples/booleans/objects).
Move tuple-based outputs into a separate interpolate() call.
Audit the array for any element that is not a string or number.

Example fix

// before
const r = interpolate(t, [0, 1], ['rotate(0deg)', [0, 1]]);
// after
const rot = interpolate(t, [0, 1], ['rotate(0deg)', 'rotate(90deg)']);

Defensive patterns

Strategy: validation

Validate before calling

const ok = outputRange.every(
  (o) => typeof o === 'string' || typeof o === 'number',
);
if (outputRange.some((o) => typeof o === 'string') && !ok) {
  throw new Error('string outputs may mix only with numbers');
}
const r = interpolate(input, inputRange, outputRange);

Type guard

const isStringOrNumberArray = (
  x: unknown[],
): x is (string | number)[] =>
  x.every((v) => typeof v === 'string' || typeof v === 'number');

Prevention

Keep CSS-string outputs in their own interpolate() call.
Never mix tuples or booleans into a string-output range.
Type string-output ranges as (string | number)[].

When it happens

Trigger: interpolate(0,[0,1],['100px', true]); interpolate(0,[0,1],['100px', [1,2]]); mixing a CSS string output with a tuple or boolean in the same outputRange.

Common situations: Combining transform-string outputs ('rotate(0deg)') with 2D tuple outputs in one array; a stray boolean from a conditional expression slipping into the array.

Related errors

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/4ab71495b5627d3d. Report an issue: GitHub.