nodejs/node · error

lgwin parameter (%d) smaller than the minimum (%d)\n

Error message

lgwin parameter (%d) smaller than the minimum (%d)\n

What it means

After a successful `ParseInt`, brotli enforces a second constraint: if `lgwin != 0` it must be `>= BROTLI_MIN_WINDOW_BITS` (10). `0` is allowed (means 'use default'). Values like `1..9` print `lgwin parameter (<v>) smaller than the minimum (<min>)` and abort. This guards against an effectively-useless tiny window.

Source

Thrown at deps/brotli/c/tools/brotli.c:476

          quality_set = ParseInt(argv[i], BROTLI_MIN_QUALITY,
                                 BROTLI_MAX_QUALITY, &params->quality);
          if (!quality_set) {
            fprintf(stderr, "error parsing quality value [%s]\n", argv[i]);
            return COMMAND_INVALID;
          }
        } else if (c == 'w') {
          if (lgwin_set) {
            fprintf(stderr, "lgwin parameter already set\n");
            return COMMAND_INVALID;
          }
          lgwin_set = ParseInt(argv[i], 0,
                               BROTLI_MAX_WINDOW_BITS, &params->lgwin);
          if (!lgwin_set) {
            fprintf(stderr, "error parsing lgwin value [%s]\n", argv[i]);
            return COMMAND_INVALID;
          }
          if (params->lgwin != 0 && params->lgwin < BROTLI_MIN_WINDOW_BITS) {
            fprintf(stderr,
                    "lgwin parameter (%d) smaller than the minimum (%d)\n",
                    params->lgwin, BROTLI_MIN_WINDOW_BITS);
            return COMMAND_INVALID;
          }
        } else if (c == 'C') {
          if (comment_set) {
            fprintf(stderr, "comment already set\n");
            return COMMAND_INVALID;
          }
          params->comment_len = MAX_COMMENT_LEN;
          if (!ParseBase64(argv[i], params->comment, &params->comment_len)) {
            fprintf(stderr, "invalid base64-encoded comment\n");
            return COMMAND_INVALID;
          }
          comment_set = BROTLI_TRUE;
        } else if (c == 'D') {
          if (params->dictionary_path) {
            fprintf(stderr, "dictionary path already set\n");

View on GitHub (pinned to 1b2de5e052)

Solutions

1. Use `0` for the default window, or a value in [10, BROTLI_MAX_WINDOW_BITS] (typically [10, 24]).
2. Re-read `brotli --help` for the lgwin range before picking a number.
3. Clamp the source variable to the valid band.

Example fix

# before
brotli -w 5 in
# after
brotli -w 0 in

# bash: lgwin must be 0 or in [10, MAXW]
MINW=10; MAXW=24
argv=("$@")
for ((i=0;i<${#argv[@]};i++)); do
  if [ "${argv[$i]}" = -w ]; then
    v=${argv[$((i+1))]:-}
    if [ "$v" != 0 ] && { [ "$v" -lt "$MINW" ] || [ "$v" -gt "$MAXW" ]; }; then
      echo "lgwin $v out of [0] or [$MINW..$MAXW]" >&2; exit 2
    fi
  fi
done
brotli "$@"

# bash
if ! brotli "$@"; then rc=$?; echo "brotli exit $rc; check lgwin range" >&2; exit "$rc"; fi

When it happens

Trigger: `brotli -w 5 in`, `brotli -w 9 in`, or any value in `1..9`.

Common situations: Confusing lgwin with quality (`-w 5` thinking 'quality 5'); auto-tuned config generating tiny numbers; copy-pasting a value tuned for a different compressor.

Related errors

• lgwin parameter already set\n
• error parsing lgwin value [%s]\n
• too many options passed
• quality already set
• write to standard output already set

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/d915e4114b10c896. Report an issue: GitHub.