What causes "Expected a bigint value, but got a %s: %s" in apache/cassandra?

Send the value as a JSON integer without a decimal point, or as a quoted string of digits.

apache/cassandra · error · MarshalException

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

Error message

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

What it means

LongType.fromJSONObject accepts a JSON string (parsed via fromString) or a JSON integer for a bigint column. If the value is a Number but not an Integer or Long (e.g. Double, Float, BigInteger), it cannot be safely narrowed to a long, so a MarshalException is thrown.

Source

Thrown at src/java/org/apache/cassandra/db/marshal/LongType.java:127

        catch (Exception e)
        {
            throw new MarshalException(String.format("Unable to make long from '%s'", source), e);
        }

        return decompose(longType);
    }

    @Override
    public Term fromJSONObject(Object parsed) throws MarshalException
    {
        try
        {
            if (parsed instanceof String)
                return new Constants.Value(fromString((String) parsed));

            Number parsedNumber = (Number) parsed;
            if (!(parsedNumber instanceof Integer || parsedNumber instanceof Long))
                throw new MarshalException(String.format("Expected a bigint value, but got a %s: %s", parsed.getClass().getSimpleName(), parsed));

            return new Constants.Value(getSerializer().serialize(parsedNumber.longValue()));
        }
        catch (ClassCastException exc)
        {
            throw new MarshalException(String.format(
                    "Expected a bigint value, but got a %s: %s", parsed.getClass().getSimpleName(), parsed));
        }
    }

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

    @Override
    public boolean isValueCompatibleWithInternal(AbstractType<?> otherType)

View on GitHub (pinned to 88fd0f6a0e)

Solutions

Send the value as a JSON integer without a decimal point, or as a quoted string of digits.
Round/convert the value to an integer client-side before sending.
If fractional values are legitimate, use a double or decimal column type instead of bigint.

Example fix

// before
{"count": 1.5}
// after
{"count": "1"}  // or {"count": 1}

Defensive patterns

Strategy: type-guard

Validate before calling

boolean ok = value instanceof String || value instanceof Integer || value instanceof Long;
if (!ok) throw new IllegalArgumentException("bigint expects a JSON integer or digit string, got: " + value.getClass().getSimpleName());

Type guard

boolean isJsonBigint(Object o) { return o instanceof Integer || o instanceof Long || (o instanceof String && isValidLong((String) o)); }

Try / catch

try { return LongType.instance.fromJSONObject(parsed); } catch (MarshalException e) { throw new BadRequestException("bigint field must be an integer: " + e.getMessage()); }

Prevention

Avoid floating-point JSON values for bigint columns.
Use string encoding for large integers to preserve precision across languages.
Configure JS clients (or use BigInt serialization) so whole numbers stay integers in JSON.

When it happens

Trigger: Using fromJson()/JSON INSERT with a bigint column whose JSON value is a floating-point number (e.g. 1.5) or an oversized integer that the JSON parser decoded as Double/BigInteger rather than Integer/Long.

Common situations: JavaScript clients serializing all numbers as doubles; JSON payloads with decimal values for count columns; very large integers from other languages exceeding double precision.

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

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/45d88c46a7ec3ae4. Report an issue: GitHub.