EC
ERR_INVALID_BUFFER_SIZE
Node.jsERRORNotableBufferHIGH confidence

Buffer size is not a multiple of the word size

Production Risk

Low — caught immediately at call site; affects binary protocol or image processing code.

What this means

Thrown when a Buffer method that operates on multi-byte values (such as buf.swap16(), buf.swap32(), buf.swap64()) is called on a buffer whose byte length is not an exact multiple of the element size (2, 4, or 8 bytes respectively). Swapping requires complete elements.

Why it happens
  1. 1Calling buf.swap16() on a buffer with an odd byte length
  2. 2Calling buf.swap32() on a buffer whose length is not divisible by 4
  3. 3Calling buf.swap64() on a buffer whose length is not divisible by 8
How to reproduce

Triggered when swap16/32/64 is called on a buffer that cannot be evenly divided into the target element size.

trigger — this will error
trigger — this will error
const buf = Buffer.from([0x01, 0x02, 0x03]); // 3 bytes
buf.swap16(); // throws — 3 is not a multiple of 2

expected output

RangeError [ERR_INVALID_BUFFER_SIZE]: Buffer size must be a multiple of 16-bits

Fix 1

Ensure the buffer length is a multiple of the swap unit

WHEN Before calling any swap method

Ensure the buffer length is a multiple of the swap unit
const buf = Buffer.from([0x01, 0x02, 0x03, 0x04]); // 4 bytes
buf.swap16(); // ok — 4 is a multiple of 2
buf.swap32(); // ok — 4 is a multiple of 4

Why this works

Swap methods require complete element pairs; ensuring the length is aligned satisfies the check.

Fix 2

Validate buffer length before swapping

WHEN When buffer size comes from external data

Validate buffer length before swapping
if (buf.length % 2 !== 0) throw new Error('Buffer must be 16-bit aligned');
buf.swap16();

Why this works

A guard prevents the swap from being called on a misaligned buffer.

Code examples
Triggerjs
const buf = Buffer.from([0x01, 0x02, 0x03]); // 3 bytes
buf.swap16(); // throws — 3 is not a multiple of 2  // this triggers ERR_INVALID_BUFFER_SIZE
Handle in try/catchjs
try {
  // operation that may throw ERR_INVALID_BUFFER_SIZE
  riskyOperation()
} catch (err) {
  if (err.code === 'ERR_INVALID_BUFFER_SIZE') {
    console.error('ERR_INVALID_BUFFER_SIZE:', err.message)
  } else {
    throw err
  }
}
Defensive pattern to avoid itjs
// Validate inputs before calling the operation
function safe_err_invalid_buffer_size(...args) {
  // validate args here
  return performOperation(...args)
}
What not to do

✕ Call swap16/32/64 without verifying alignment

Unaligned buffers cannot be swapped in place; the operation is undefined for partial elements.

Same error in other languages
ValueErrorin Python→
Sources
Official documentation ↗

Node.js Error Codes Documentation

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