apache/flink · error · RuntimeException

Type information for input of type {} is not supported. Coul

Error message

Type information for input of type {} is not supported. Could not generate a comparator.

What it means

Error "Type information for input of type {} is not supported. Could not generate a comparator." thrown in apache/flink.

Source

Thrown at flink-core/src/main/java/org/apache/flink/api/common/operators/base/OuterJoinOperatorBase.java:178

        return result;
    }

    @SuppressWarnings("unchecked")
    private <T> TypeComparator<T> buildComparatorFor(
            int input, ExecutionConfig executionConfig, TypeInformation<T> typeInformation) {
        TypeComparator<T> comparator;
        if (typeInformation instanceof AtomicType) {
            comparator = ((AtomicType<T>) typeInformation).createComparator(true, executionConfig);
        } else if (typeInformation instanceof CompositeType) {
            int[] keyPositions = getKeyColumns(input);
            boolean[] orders = new boolean[keyPositions.length];
            Arrays.fill(orders, true);

            comparator =
                    ((CompositeType<T>) typeInformation)
                            .createComparator(keyPositions, orders, 0, executionConfig);
        } else {
            throw new RuntimeException(
                    "Type information for input of type "
                            + typeInformation.getClass().getCanonicalName()
                            + " is not supported. Could not generate a comparator.");
        }
        return comparator;
    }

    private static class OuterJoinListIterator<IN1, IN2> {

        private static enum MatchStatus {
            NONE_REMAINED,
            FIRST_REMAINED,
            SECOND_REMAINED,
            FIRST_EMPTY,
            SECOND_EMPTY
        }

        private OuterJoinType outerJoinType;

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Address the cause reported by the error message: Type information for input of type the reported value is not supported. Could not generate a comparator.
2. Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry.

Example fix

Correct the condition described ("Type information for input of type the reported value is not supported. Could not generate a comparator.") and rerun the job or command.

When it happens

Trigger: Triggered at runtime when the operation fails because: Type information for input of type the reported value is not supported. Could not generate a comparator.

Common situations: Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: Type information for input of type the reported value is not supported. Could not generate a comparator.

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/3336d9f4a815239b. Report an issue: GitHub.