This error occurs when attempting to allocate a Node.js Buffer with an invalid size—typically negative, zero, or exceeding platform limits. Buffer.alloc() and Buffer.allocUnsafe() enforce strict validation to prevent memory allocation failures.
Node.js enforces strict validation on Buffer allocation sizes for safety and reliability. The RangeError is thrown when the size argument is negative, zero, or exceeds the maximum allowed buffer size (typically 2,147,483,647 bytes on 32-bit systems). This validation prevents undefined behavior and memory corruption that could occur with invalid memory allocations.
Check that the size argument is a positive integer before passing it to Buffer allocation methods. Add validation immediately before the allocation call:
const size = calculateBufferSize(data);
// Add validation
if (typeof size !== 'number' || size <= 0) {
throw new Error('Buffer size must be a positive number');
}
const buffer = Buffer.alloc(size);Use explicit guards to catch invalid sizes early in development and in production.
Review any arithmetic operations that produce the buffer size. Ensure subtraction operations won't produce negative results:
// Bad: can result in negative size
const buffer = Buffer.alloc(dataLength - offset);
// Good: validate before allocation
const allocSize = Math.max(0, dataLength - offset);
if (allocSize === 0) {
console.warn('Buffer size would be zero, skipping allocation');
return null;
}
const buffer = Buffer.alloc(allocSize);Use Math.max() to ensure minimum values, or add explicit range checks.
If the buffer size comes from user input, query parameters, or API requests, validate and sanitize strictly:
const userInputSize = parseInt(req.query.bufferSize);
// Validation checks
if (isNaN(userInputSize) || userInputSize < 1 || userInputSize > 1000000) {
return res.status(400).json({ error: 'Invalid buffer size' });
}
const buffer = Buffer.alloc(userInputSize);Define minimum and maximum limits based on your use case, and reject out-of-range values explicitly.
Combine number validation with integer checks to catch type coercion issues:
const size = someCalculation();
if (!Number.isInteger(size) || size <= 0) {
throw new TypeError(
`Expected positive integer for buffer size, got ${size}`
);
}
const buffer = Buffer.alloc(size);This prevents accidentally passing floating-point numbers or strings that coerce to unexpected values.
For large buffers, validate against platform limits before allocation:
const requestedSize = calculateSize(data);
const MAX_BUFFER_SIZE = Buffer.constants.MAX_LENGTH;
if (requestedSize > MAX_BUFFER_SIZE) {
throw new RangeError(
`Requested buffer size ${requestedSize} exceeds maximum ${MAX_BUFFER_SIZE}`
);
}
const buffer = Buffer.alloc(requestedSize);This prevents ERR_BUFFER_TOO_LARGE errors on extremely large allocations.
The deprecated Buffer(size) constructor has been removed in favor of Buffer.alloc(), Buffer.allocUnsafe(), and Buffer.allocUnsafeSlow() because these new methods enforce strict validation. Buffer.alloc() initializes memory to zero (safer for sensitive data but slower), while Buffer.allocUnsafe() skips initialization (faster but requires care). Both validate that size > 0 and size <= Buffer.constants.MAX_LENGTH. In streaming scenarios, validate chunk sizes before creating buffers. For memory-constrained environments, consider using object pooling or streaming APIs (fs.createReadStream, http.IncomingMessage) instead of allocating large buffers upfront.
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