apache/flink · error · IllegalArgumentException

Join Hint must not be null.

Error message

Join Hint must not be null.

What it means

Error "Join Hint must not be null." thrown in apache/flink.

Source

Thrown at flink-core/src/main/java/org/apache/flink/api/common/operators/base/JoinOperatorBase.java:114

            BinaryOperatorInformation<IN1, IN2, OUT> operatorInfo,
            int[] keyPositions1,
            int[] keyPositions2,
            String name) {
        super(new UserCodeObjectWrapper<>(udf), operatorInfo, keyPositions1, keyPositions2, name);
    }

    public JoinOperatorBase(
            Class<? extends FT> udf,
            BinaryOperatorInformation<IN1, IN2, OUT> operatorInfo,
            int[] keyPositions1,
            int[] keyPositions2,
            String name) {
        super(new UserCodeClassWrapper<>(udf), operatorInfo, keyPositions1, keyPositions2, name);
    }

    public void setJoinHint(JoinHint joinHint) {
        if (joinHint == null) {
            throw new IllegalArgumentException("Join Hint must not be null.");
        }
        this.joinHint = joinHint;
    }

    public JoinHint getJoinHint() {
        return joinHint;
    }

    public void setCustomPartitioner(Partitioner<?> partitioner) {
        this.partitioner = partitioner;
    }

    public Partitioner<?> getCustomPartitioner() {
        return partitioner;
    }
}

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Address the cause reported by the error message: Join Hint must not be null.
2. Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry.

Example fix

Correct the condition described ("Join Hint must not be null.") and rerun the job or command.

When it happens

Trigger: Triggered at runtime when the operation fails because: Join Hint must not be null.

Common situations: Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: Join Hint must not be null.

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/40625228f5f5a3dc. Report an issue: GitHub.