apache/druid · error · IllegalArgumentException

Invalid format of number: %s

Error message

Invalid format of number: %s

What it means

HumanReadableBytes.parseInner throws this IllegalArgumentException when the string ends in 'b' but is too short or malformed to be a binary unit like KiB/MiB/GiB/TiB/PiB — the parser requires at least three characters before the final 'b' (a digit and a binary prefix such as 'Ki').

Source

Thrown at processing/src/main/java/org/apache/druid/java/util/common/HumanReadableBytes.java:156

      return nullValue;
    }
    return parseInner(number);
  }

  private static long parseInner(String rawNumber)
  {
    String number = StringUtils.toLowerCase(rawNumber);
    if (number.charAt(0) == '-') {
      throw new IAE("Invalid format of number: %s. Negative value is not allowed.", rawNumber);
    }

    int lastDigitIndex = number.length() - 1;
    boolean isBinaryByte = false;
    char unit = number.charAt(lastDigitIndex--);
    if (unit == 'b') {
      //unit ends with 'b' must be format of KiB/MiB/GiB/TiB/PiB, so at least 3 extra characters are required
      if (lastDigitIndex < 2) {
        throw new IAE("Invalid format of number: %s", rawNumber);
      }
      if (number.charAt(lastDigitIndex--) != 'i') {
        throw new IAE("Invalid format of number: %s", rawNumber);
      }

      unit = number.charAt(lastDigitIndex--);
      isBinaryByte = true;
    } else if (unit == 'i') {
      //unit ends with 'i' must be format of Ki/Mi/Gi/Ti/Pi, so at least 2 extra characters are required
      if (lastDigitIndex < 1) {
        throw new IAE("Invalid format of number [%s]. The unit should be one of Pi/Ti/Gi/Mi/Ki", rawNumber);
      }
      unit = number.charAt(lastDigitIndex--);
      isBinaryByte = true;
    }

    long base = 1;
    switch (unit) {

View on GitHub (pinned to 9b90983fd2)

Solutions

  1. Use a plain number for bytes (e.g. "1024" instead of "1024b")
  2. Use the correct binary form "KiB"/"MiB" etc. if a binary unit was intended (e.g. "128MiB")
  3. Use decimal units like "mb"/"gb" for powers of 1000 instead of trailing 'b'
  4. Catch IAE and display the accepted formats (digits, K/M/G/T/P, KiB/MiB/...) in validation UI

Example fix

// before
long bytes = HumanReadableBytes.parse("1024b"); // invalid
// after
long bytes = HumanReadableBytes.parse("1024"); // plain bytes
Defensive patterns

Strategy: validation

Validate before calling

private static final Pattern HUMAN_BYTES = Pattern.compile("^\\d+\\s*(k|m|g|t|p)?(i?[b]?)?$", Pattern.CASE_INSENSITIVE);
if (raw == null || !HUMAN_BYTES.matcher(raw.trim()).matches()) {
  throw new IllegalArgumentException("Invalid byte size format: " + raw);
}

Try / catch

try {
  long bytes = HumanReadableBytes.parse(raw);
} catch (IAE e) {
  throw new IllegalArgumentException("Bad size string '" + raw + "'; use forms like 1024, 100mb, 128MiB", e);
}

Prevention

When it happens

Trigger: Calling parse with inputs like "b", "5b", "kib" (no digits), or "12b" — anything ending in 'b' lacking the required Ki/Mi/Gi/Ti/Pi prefix pattern.

Common situations: Users writing "1024b" expecting a plain-bytes suffix (the library treats trailing 'b' as binary-unit syntax); typo'd units like "mb" written as lowercase plus 'b' confusion; abbreviated docs examples.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/ca6b0a0b1084876a. Report an issue: GitHub.