apache/cassandra · warning · IllegalArgumentException

value %s is not a valid human-readable file size

Error message

value %s is not a valid human-readable file size

What it means

parseFileSize(String) throws IllegalArgumentException when the input does not match the pattern '\d+(\.\d+)? (GiB|KiB|MiB|TiB|bytes)' — a number, one space, and one of the exact binary units. The format is strict: no 'KB'/'GB' decimal units, no missing space, no bare numbers.

Source

Thrown at src/java/org/apache/cassandra/io/util/FileUtils.java:332

    }

    public static String getCanonicalPath(File file)
    {
        return file.canonicalPath();
    }

    /** Return true if file is contained in folder */
    public static boolean isContained(File folder, File file)
    {
        return folder.isAncestorOf(file);
    }

    public static long parseFileSize(String value)
    {
        long result;
        if (!value.matches("\\d+(\\.\\d+)? (GiB|KiB|MiB|TiB|bytes)"))
        {
            throw new IllegalArgumentException(
                String.format("value %s is not a valid human-readable file size", value));
        }
        if (value.endsWith(" TiB"))
        {
            result = Math.round(Double.valueOf(value.replace(" TiB", "")) * ONE_TIB);
            return result;
        }
        else if (value.endsWith(" GiB"))
        {
            result = Math.round(Double.valueOf(value.replace(" GiB", "")) * ONE_GIB);
            return result;
        }
        else if (value.endsWith(" KiB"))
        {
            result = Math.round(Double.valueOf(value.replace(" KiB", "")) * ONE_KIB);
            return result;
        }
        else if (value.endsWith(" MiB"))

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Format the value as '<number> <UNIT>' with a single space and unit in {bytes, KiB, MiB, GiB, TiB}.
2. Convert decimal units (MB→MiB etc.) or rewrite as raw byte counts elsewhere.
3. Pre-parse/validate with the same regex before calling.

Example fix

// before
FileUtils.parseFileSize("10MB"); // throws

// after
FileUtils.parseFileSize("10 MiB"); // OK

private static final Pattern SIZE = Pattern.compile("\\d+(\\.\\d+)? (GiB|KiB|MiB|TiB|bytes)");
boolean isValidSize(String v) { return v != null && SIZE.matcher(v).matches(); }

boolean isHumanReadableSize(String v) { return v != null && v.matches("\\d+(\\.\\d+)? (GiB|KiB|MiB|TiB|bytes)"); }

try { long n = FileUtils.parseFileSize(v); } catch (IllegalArgumentException e) { /* normalize unit and retry */ }

When it happens

Trigger: Calling FileUtils.parseFileSize with values like '10MB', '10 MB', '1024', '1.5 GiB ' (trailing space), or lowercase 'mib'.

Common situations: Users writing cassandra.yaml-style sizes with decimal units (MB/GB) into APIs expecting binary human-readable units; programmatic config generation emitting unspaced or unprefixed values; whitespace/case mistakes.

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

• Commit log position must be given as <segment>,<position>
• Unexpected string: ${tokenScanner.next()}
• Invalid modifier specification: '${spec.substring(next, end)
• Invalid TokenRange:
• %s is not a valid function resource name. It must end with "

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/15a2fbefb196b9f4. Report an issue: GitHub.