prestodb/presto · error · UnsupportedOperationException

Unsupported task content: ${task.getContent()}

Error message

Unsupported task content: ${task.getContent()}

What it means

Raised when a commit task written by a worker carries a TableCommitMetadata content type that this Presto/Iceberg version does not know how to finish. The finishWrite dispatcher only handles POSITION_DELETE and DATA content kinds; anything else (e.g. EQUALITY_DELETES) hits the default branch and throws UnsupportedOperationException.

Source

Thrown at presto-iceberg/src/main/java/com/facebook/presto/iceberg/IcebergAbstractMetadata.java:850

                .toArray(Type[]::new);
        handleFinishData(task, icebergTable, partitionSpec, partitionColumnTypes, appendFiles::appendFile, writtenFiles);
    }

    private void handleTask(CommitTaskData task, Table icebergTable, RowDelta rowDelta, ImmutableSet.Builder<String> writtenFiles, ImmutableSet.Builder<String> referencedDataFiles)
    {
        PartitionSpec partitionSpec = icebergTable.specs().get(task.getPartitionSpecId());
        Type[] partitionColumnTypes = partitionSpec.fields().stream()
                .map(field -> field.transform().getResultType(icebergTable.schema().findType(field.sourceId())))
                .toArray(Type[]::new);
        switch (task.getContent()) {
            case POSITION_DELETES:
                handleFinishPositionDeletes(task, partitionSpec, partitionColumnTypes, rowDelta, writtenFiles, referencedDataFiles);
                break;
            case DATA:
                handleFinishData(task, icebergTable, partitionSpec, partitionColumnTypes, rowDelta::addRows, writtenFiles);
                break;
            default:
                throw new UnsupportedOperationException("Unsupported task content: " + task.getContent());
        }
    }

    private void handleFinishPositionDeletes(CommitTaskData task, PartitionSpec partitionSpec, Type[] partitionColumnTypes, RowDelta rowDelta, ImmutableSet.Builder<String> writtenFiles, ImmutableSet.Builder<String> referencedDataFiles)
    {
        FileMetadata.Builder deleteBuilder = FileMetadata.deleteFileBuilder(partitionSpec)
                .withPath(task.getPath())
                .withFormat(task.getFileFormat().toIceberg())
                .ofPositionDeletes()
                .withFileSizeInBytes(task.getFileSizeInBytes())
                .withMetrics(task.getMetrics().metrics());

        if (!partitionSpec.fields().isEmpty()) {
            String partitionDataJson = task.getPartitionDataJson()
                    .orElseThrow(() -> new VerifyException("No partition data for partitioned table"));
            deleteBuilder.withPartition(PartitionData.fromJson(partitionDataJson, partitionColumnTypes));
        }

View on GitHub (pinned to 55bb57d202)

Solutions

1. Upgrade Presto to a version whose IcebergMetadata handles the task content type being produced.
2. Ensure the table's UPDATE_MODE / delete strategy produces position deletes (merge-on-read with position deletes) rather than equality deletes.
3. Avoid running row-level DML through an engine that doesn't support the delete-file type for the table's format version.

Example fix

// before
-- equality-delete-producing engine commits tasks Presto cannot finish
-- after
SET SESSION iceberg.update_mode = 'merge-on-read'; -- use supported position-delete path, or upgrade Presto

// confirm engine support before DML
SELECT format_version FROM "t$properties"; -- ensure supported delete strategy
SELECT value FROM "t$properties" WHERE key = 'write.delete.mode';

try { dml(...); }
catch (UnsupportedOperationException e) { /* upgrade connector or use position-delete-producing mode */ }

When it happens

Trigger: finishWrite processes CommitTaskData whose getContent() is neither DATA nor POSITION_DELETE — typically a table whose write plan produced equality delete files, or a mixed engine/version deployment writing new delete kinds the reader doesn't support.

Common situations: Reading/committing a table written by a newer engine that emits equality deletes; a Presto version too old to handle the delete-file kind produced during row-level DML.

Related errors

• NOT_SUPPORTED
• NOT_SUPPORTED
• NOT_SUPPORTED
• ICEBERG_UNKNOWN_MANIFEST_TYPE
• NOT_SUPPORTED

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/1038ffd5a21c0fc5. Report an issue: GitHub.