apache/iceberg · error · UnsupportedOperationException

${this.getClass().getName()} doesn't implement copyWithLengt

Error message

${this.getClass().getName()} doesn't implement copyWithLength

What it means

NativeEncryptionKeyMetadata.copyWithLength is a default method that throws UnsupportedOperationException. It must be overridden to return a copy of the key metadata carrying the given encrypted file length; the default signals the implementation does not support length tracking.

Source

Thrown at core/src/main/java/org/apache/iceberg/encryption/NativeEncryptionKeyMetadata.java:44

  ByteBuffer encryptionKey();

  /** Additional authentication data as a {@link ByteBuffer} */
  ByteBuffer aadPrefix();

  /** Encrypted file length */
  default Long fileLength() {
    throw new UnsupportedOperationException(
        this.getClass().getName() + " doesn't implement fileLength");
  }

  /**
   * Copy this key metadata and set the file length.
   *
   * @param length length of the encrypted file in bytes
   * @return a copy of this key metadata (key and AAD) with the file length
   */
  default NativeEncryptionKeyMetadata copyWithLength(long length) {
    throw new UnsupportedOperationException(
        this.getClass().getName() + " doesn't implement copyWithLength");
  }
}

View on GitHub (pinned to 86d9c8fc54)

Solutions

Override copyWithLength(long) in your implementation to return a copy with the length set
Use a key metadata implementation that supports length copying
Update the library providing the key metadata class to a version that implements it

Example fix

// before
class MyKeyMetadata implements NativeEncryptionKeyMetadata { /* no copyWithLength */ }
// after
class MyKeyMetadata implements NativeEncryptionKeyMetadata {
  @Override public NativeEncryptionKeyMetadata copyWithLength(long length) {
    return new MyKeyMetadata(kekId(), keyId(), aadPrefix(), length);
  }
}

Defensive patterns

Strategy: try-catch

Validate before calling

try { km.copyWithLength(0L); return true; } catch (UnsupportedOperationException e) { return false; }

Try / catch

try { withLength = km.copyWithLength(length); }
catch (UnsupportedOperationException e) { withLength = null; /* impl lacks length support */ }

Prevention

Override copyWithLength in every NativeEncryptionKeyMetadata implementation
Keep custom key metadata classes in sync with interface additions
Add integration tests that call copyWithLength during file writing

When it happens

Trigger: Calling copyWithLength(length) on a NativeEncryptionKeyMetadata implementation that did not override it, typically when a writer needs to attach the final encrypted file size to key metadata.

Common situations: Custom or older native encryption key metadata implementations predating copyWithLength; third-party integration code that never implemented the length-copy contract.

Related errors

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/aa2e3bef72173a6e. Report an issue: GitHub.