apache/cassandra · error · MarshalException

Value '%s' is not a valid representation of a decimal value

Error message

Value '%s' is not a valid representation of a decimal value

What it means

DecimalType.fromJSONObject converts the JSON value to a string and calls fromString; NumberFormatException or MarshalException from that parse is rethrown as this MarshalException naming the offending JSON value. It exists to give JSON-import flows a clear, value-specific message.

Source

Thrown at src/java/org/apache/cassandra/db/marshal/DecimalType.java:309

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

        return decompose(decimal);
    }

    @Override
    public Term fromJSONObject(Object parsed) throws MarshalException
    {
        try
        {
            return new Constants.Value(fromString(Objects.toString(parsed)));
        }
        catch (NumberFormatException | MarshalException exc)
        {
            throw new MarshalException(String.format("Value '%s' is not a valid representation of a decimal value", parsed));
        }
    }

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

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

    public TypeSerializer<BigDecimal> getSerializer()
    {
        return DecimalSerializer.instance;
    }

View on GitHub (pinned to 88fd0f6a0e)

Solutions

Fix the JSON document so the decimal field is a number or a valid decimal string
Coerce/validate the field before calling fromJSONObject
Map bad rows to a dead-letter log instead of failing the whole import

Example fix

// before
{"amount": "12.3.4"}
// after
{"amount": "12.34"}

Defensive patterns

Strategy: try-catch

Validate before calling

Object v = json.get("amount"); boolean ok = v instanceof Number || (v instanceof String && isDecimalLiteral((String) v));

Type guard

boolean isValidDecimalJson(Object v) { return v instanceof Number || (v instanceof String && v.toString().matches("[+-]?\\d+(\\.\\d+)?")); }

Try / catch

try { DecimalType.instance.fromJSONObject(parsed); } catch (MarshalException e) { /* log parsed value, route row to error queue */ }

Prevention

Pre-validate JSON decimal fields (number or numeric string)
Reject booleans/nulls at the JSON schema level
Handle per-row failures instead of aborting the whole import

When it happens

Trigger: fromJSONObject invoked with a JSON value whose string form is not a valid decimal (e.g. true, null-converted string, '12.3.4').

Common situations: COPY FROM JSON, cqlsh JSON input, or driver JSON serialization emitting booleans/nulls/strings into decimal columns.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/bb9625cf95a924a4. Report an issue: GitHub.