apache/cassandra · error · IllegalArgumentException

Value '%s' can't be converted to integer.

Error message

Value '%s' can't be converted to integer.

What it means

Thrown by UUIDRoleNameGenerator.getSize() when the 'name_size' option is a String that Integer.parseInt cannot convert (or a completely unsupported object type). The message includes the offending value.

Source

Thrown at src/java/org/apache/cassandra/db/guardrails/UUIDRoleNameGenerator.java:176

            else
                throw new IllegalArgumentException("Value of " + NAME_SIZE + " has to be strictly positive integer.");
        }
        else
        {
            sizeObject = MAXIMUM_NAME_SIZE;
        }

        int size;

        if (sizeObject instanceof String)
        {
            try
            {
                size = Integer.parseInt((String) sizeObject);
            }
            catch (Throwable t)
            {
                throw new IllegalArgumentException("Value '" + sizeObject + "' can't be converted to integer.");
            }
        }
        else if (sizeObject instanceof Number)
            size = ((Number) sizeObject).intValue();
        else
            throw new IllegalArgumentException("Unsupported object passed to resolve " + NAME_SIZE + ": " + sizeObject.getClass().getName());

        if (size < minimumNameSize)
            throw new IllegalArgumentException("Value of " + NAME_SIZE + " parameter has to be at least " + minimumNameSize + '.');

        if (size > MAXIMUM_NAME_SIZE)
            throw new IllegalArgumentException("Generator generates names of maximum length " + MAXIMUM_NAME_SIZE + ". " +
                                               "You want to generate with length " + size + '.');

        return size;
    }
}

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Pass name_size as a whole-number string like "8" or as an integer Number type
2. Trim whitespace and avoid decimals/suffixes in the string value
3. Handle the unsupported-type branch: only String or Number instances are accepted

Example fix

// before
options.put("name_size", "8.5");
// after
options.put("name_size", "8");

Object v = options.get("name_size");
if (v instanceof String s && !s.trim().matches("\\d+"))
    throw new IllegalArgumentException("name_size must be a whole number string");

boolean isParsableSize(Object v) {
    if (v instanceof Number) return true;
    if (v instanceof String) try { Integer.parseInt((String) v); return true; } catch (Exception e) { return false; }
    return false;
}

try {
    generator.generate(options);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("can't be converted to integer")) {
        // parse/normalize name_size client-side, then retry
    } else throw e;
}

When it happens

Trigger: Passing name_size as a non-numeric string like "eight" or "8.5" or " 8" (whitespace), or as an unsupported object (e.g. Boolean, List) that is neither String nor Number.

Common situations: Users writing fractional or formatted numbers ('8.0', '1_0'), or config frameworks deserializing the value as a Float/Boolean.

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

• Value of %s is not a string.
• Unsupported object passed to resolve name_size: %s
• Value of %s cannot be null.
• Unexpected string: ${tokenScanner.next()}
• Unhandled return type:

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/6f5541acc591dd71. Report an issue: GitHub.