apache/beam · error · UnsupportedOperationException

Writing ZIP files is currently unsupported

Error message

Writing ZIP files is currently unsupported

What it means

Beam can read ZIP-compressed inputs (via FullZipInputStream) but has no ZIP writer; the ZIP variant of writeCompressed() unconditionally throws UnsupportedOperationException. Writing ZIP output is simply not implemented.

Source

Thrown at sdks/java/core/src/main/java/org/apache/beam/sdk/io/Compression.java:133

    @Override
    public WritableByteChannel writeCompressed(WritableByteChannel channel) throws IOException {
      return Channels.newChannel(
          new BZip2CompressorOutputStream(Channels.newOutputStream(channel)));
    }
  },

  /** Zip compression. */
  ZIP(".zip", ".zip") {
    @Override
    public ReadableByteChannel readDecompressed(ReadableByteChannel channel) throws IOException {
      FullZipInputStream zip = new FullZipInputStream(Channels.newInputStream(channel));
      return Channels.newChannel(zip);
    }

    @Override
    public WritableByteChannel writeCompressed(WritableByteChannel channel) throws IOException {
      throw new UnsupportedOperationException("Writing ZIP files is currently unsupported");
    }
  },

  /**
   * ZStandard compression.
   *
   * <p>The {@code .zst} extension is specified in <a href=https://tools.ietf.org/html/rfc8478>RFC
   * 8478</a>.
   *
   * <p>The Beam Java SDK does not pull in the Zstd library by default, so it is the user's
   * responsibility to declare an explicit dependency on {@code zstd-jni}. Attempts to read or write
   * .zst files without {@code zstd-jni} loaded will result in {@code NoClassDefFoundError} at
   * runtime.
   */
  ZSTD(".zst", ".zst", ".zstd") {
    @Override
    public ReadableByteChannel readDecompressed(ReadableByteChannel channel) throws IOException {
      return Channels.newChannel(new ZstdCompressorInputStream(Channels.newInputStream(channel)));

View on GitHub (pinned to 12126d8942)

Solutions

1. Write with a supported compression (GZIP, BZIP2, or ZSTD) instead of ZIP.
2. Write UNCOMPRESSED output and compress externally in a downstream job step if ZIP is mandatory.
3. Add a custom sink wrapper that compresses output bytes into a zip archive yourself.

Example fix

// before
.withCompression(Compression.ZIP)
// after
.withCompression(Compression.GZIP)

if (compression == Compression.ZIP) {
  throw new IllegalArgumentException("ZIP output unsupported; use GZIP/BZIP2/ZSTD");
}

try {
  out = compression.writeCompressed(channel);
} catch (UnsupportedOperationException e) {
  out = Compression.GZIP.writeCompressed(channel);
}

When it happens

Trigger: Configuring an output sink with ZIP compression, e.g., FileIO.write().withCompression(Compression.ZIP) or TextIO sinks whose compression resolves to ZIP.

Common situations: Users assuming read/write symmetry across compression types; config templates that set zip for all IO; migrating gzip outputs to zip without checking support.

Related errors

• Must resolve compression into a concrete value before callin
• AUTO is applicable only to reading files
• Unsupported compression type: " + compression
• Failed to determine if the source is splittable
• AUTO is not supported for writing

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/5cd686a97461051c. Report an issue: GitHub.