apache/cassandra · error · MarshalException

Expected a boolean value, but got a %s: %s

Error message

Expected a boolean value, but got a %s: %s

What it means

BooleanType.fromJSONObject throws this when a JSON value for a boolean column is neither a JSON string nor a JSON boolean. Strings go through fromString; any other JSON type (number, object, array) is rejected with the Java class simple name and value in the message.

Source

Thrown at src/java/org/apache/cassandra/db/marshal/BooleanType.java:102

    public ByteBuffer fromString(String source) throws MarshalException
    {

        if (source.isEmpty()|| source.equalsIgnoreCase(Boolean.FALSE.toString()))
            return decompose(false);

        if (source.equalsIgnoreCase(Boolean.TRUE.toString()))
            return decompose(true);

        throw new MarshalException(String.format("Unable to make boolean from '%s'", source));
    }

    @Override
    public Term fromJSONObject(Object parsed) throws MarshalException
    {
        if (parsed instanceof String)
            return new Constants.Value(fromString((String) parsed));
        else if (!(parsed instanceof Boolean))
            throw new MarshalException(String.format(
                    "Expected a boolean value, but got a %s: %s", parsed.getClass().getSimpleName(), parsed));

        return new Constants.Value(getSerializer().serialize((Boolean) parsed));
    }

    @Override
    public String toJSONString(ByteBuffer buffer, ProtocolVersion protocolVersion)
    {
        return getSerializer().deserialize(buffer).toString();
    }

    public CQL3Type asCQL3Type()
    {
        return CQL3Type.Native.BOOLEAN;
    }

    public TypeSerializer<Boolean> getSerializer()
    {

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Send a JSON boolean: {"flag": true} (or a quoted "true"/"false" string)
2. Convert 0/1 to true/false in application code before JSON insert
3. Change column type to tinyint if numeric flags are the real requirement
4. Validate JSON payload against column types before sending

Example fix

// before
INSERT INTO t JSON '{"flag": 1}';
// after
INSERT INTO t JSON '{"flag": true}';

Object v = jsonNode.isTextual() ? jsonNode.textValue() : (jsonNode.isBoolean() ? jsonNode.booleanValue() : REJECT);

boolean isBooleanJson(Object v) { return v instanceof Boolean || (v instanceof String && (((String) v).equalsIgnoreCase("true") || ((String) v).equalsIgnoreCase("false"))); }

try { Term t = boolType.fromJSONObject(parsed); } catch (MarshalException e) { if (e.getMessage().startsWith("Expected a boolean value")) { /* coerce 0/1 -> true/false */ } else throw e; }

When it happens

Trigger: INSERT INTO t JSON '{"flag": 1}' where flag is boolean (JSON number not allowed); fromJson() with numeric argument for boolean column; Term.fromJSONObject receiving e.g. Integer or Double for a boolean field.

Common situations: JSON APIs that encode booleans as 0/1; hand-written JSON payloads using unquoted 1/0; ORMs or serializers emitting integers for booleans; older payloads written before the column became boolean.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Expected an ascii string, but got a %s: %s
• Unable to make boolean from '%s'
• Expected a byte value, but got a %s: %s
• String representation of blob is missing 0x prefix: %s
• Value '%s' is not a valid blob representation: %s

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/e63d53c850f043ae. Report an issue: GitHub.