remotion-dev/remotion · error · Error

${name} must contain only numbers

Error message

${name} must contain only numbers

What it means

Thrown by checkInfiniteRange when inputRange or outputRange contains an element whose typeof is not 'number'. Strings, booleans, objects, null, and undefined inside the 1-D numeric ranges are rejected before any interpolation math runs. The name in the message is the offending array ('inputRange' or 'outputRange').

Source

Thrown at packages/core/src/interpolate.ts:1027

	for (let i = 1; i < arr.length; ++i) {
		if (!(arr[i] > arr[i - 1])) {
			throw new Error(
				`inputRange must be strictly monotonically increasing but got [${arr.join(
					',',
				)}]`,
			);
		}
	}
}

function checkInfiniteRange(name: string, arr: readonly number[]) {
	if (arr.length < 1) {
		throw new Error(name + ' must have at least 1 element');
	}

	for (const element of arr) {
		if (typeof element !== 'number') {
			throw new Error(`${name} must contain only numbers`);
		}

		if (!Number.isFinite(element)) {
			throw new Error(
				`${name} must contain only finite numbers, but got [${arr.join(',')}]`,
			);
		}
	}
}

export function assertValidInterpolateEasingOption(
	easing: EasingFunction | readonly EasingFunction[] | undefined,
	inputRangeLength: number,
) {
	if (easing === undefined) {
		return;
	}

View on GitHub (pinned to 78fe4bb3fd)

Solutions

1. Coerce every element with Number() and verify none become NaN.
2. Strip units and quotes from the source data before building the range.
3. Type the range as number[] and let TypeScript flag non-number assignments.

Example fix

// before
const r = interpolate(t, [0, '1'], [0, 100]);
// after
const r = interpolate(t, [0, Number('1')], [0, 100]);

const isAllNumbers = (arr: readonly unknown[]): arr is number[] =>
  arr.every((v) => typeof v === 'number');

if (!isAllNumbers(inputRange) || !isAllNumbers(outputRange)) {
  throw new Error('ranges must contain only numbers');
}
const r = interpolate(input, inputRange, outputRange);

const isNumberArray = (arr: readonly unknown[]): arr is number[] =>
  arr.every((v) => typeof v === 'number');

When it happens

Trigger: interpolate(0, [0, '1'], [0, 100]); interpolate(0, [0, 1], [0, null]); a range built from JSON-parsed values that arrived as strings; an array containing undefined from a sparse source.

Common situations: Parsing config/props as JSON where numbers deserialize as strings; mixing a string unit like '100px' into a numeric outputRange; optional fields rendered as undefined.

Related errors

• outputRange tuples must contain only finite numbers, but got
• Cannot interpolate an input which is not a number
• outputRange must contain only numbers
• outputRange must contain only numbers, numeric tuples, or su
• inputRange must be strictly monotonically increasing but got

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/65ab0f2cf72f140c. Report an issue: GitHub.