apache/iceberg · error · UncheckedIOException

Failed to close dvFileWriter

Error message

Failed to close dvFileWriter

What it means

BaseTaskWriter's close() closes its internal delete-vector file writer and rethrows any IOException as UncheckedIOException. This surfaces an I/O failure (flush/close to the underlying OutputFile) that happened while finalizing delete-vector files during task completion or abort.

Source

Thrown at core/src/main/java/org/apache/iceberg/io/BaseTaskWriter.java:174

        .build();
  }

  @Override
  public void close() throws IOException {
    try {
      if (dvFileWriter != null) {
        try {
          // complete will call close
          dvFileWriter.close();
          DeleteWriteResult result = dvFileWriter.result();
          completedDeleteFiles.addAll(result.deleteFiles());
          referencedDataFiles.addAll(result.referencedDataFiles());
        } finally {
          dvFileWriter = null;
        }
      }
    } catch (IOException e) {
      throw new UncheckedIOException("Failed to close dvFileWriter", e);
    }
  }

  /** Base equality delta writer to write both insert records and equality-deletes. */
  protected abstract class BaseEqualityDeltaWriter implements Closeable {
    private final StructProjection structProjection;
    private final PositionDelete<T> positionDelete;
    private final StructLike partitionKey;
    private RollingFileWriter dataWriter;
    private RollingEqDeleteWriter eqDeleteWriter;
    private PartitioningWriter<PositionDelete<T>, DeleteWriteResult> posDeleteWriter;
    private Map<StructLike, PathOffset> insertedRowMap;
    private boolean closePosDeleteWriter;

    protected BaseEqualityDeltaWriter(StructLike partition, Schema schema, Schema deleteSchema) {
      this(partition, schema, deleteSchema, DeleteGranularity.PARTITION, null);
    }

View on GitHub (pinned to 86d9c8fc54)

Solutions

1. Inspect the cause chain (getCause()) for the underlying IOException and fix that root cause in the FileIO or filesystem.
2. Ensure the task writer is closed exactly once and not after its output streams were independently closed.
3. Verify the OutputFile location is writable and the FileIO is not already closed when the task writer completes.

Example fix

// before
FileIO io = ...; io.close(); writer.close(); // IO closed before writer
// after
writer.close(); // finalize writers first
io.close();

try {
  taskWriter.close();
} catch (UncheckedIOException e) {
  LOG.error("DV writer close failed", e.getCause());
  throw e; // task must fail; fix underlying FileIO
}

When it happens

Trigger: An IOException occurs while closing the DV writer, typically from the underlying OutputFile/stream failing (closed stream, IO provider error, disk/FS error in wrapped FileIO) during complete() or abort().

Common situations: Underlying FileIO throwing on close (e.g., mocked InMemory IO closed prematurely, network file systems failing during final flush); closing the task writer twice or after the output stream was already closed elsewhere in custom writer code.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

• Failed to close manifest reader
• Failed to close entries while caching changes
• Failed to close
• Failed to close current writer
• Failed to write delete manifests

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/ad4870910d8f2a63. Report an issue: GitHub.