apache/iceberg · warning

Failed to scan delegate parser in {}:

Error message

Failed to scan delegate parser in {}: 

What it means

ExtendedParser in the Spark 4.0 connector wraps Spark's SQL parser to support extended SQL syntax. getNextDelegateParser reflectively scans the delegate parser class hierarchy for an inner ParserInterface value; if reflection fails, this warning is logged and null is returned, so findParser falls back to the standard parsing path.

Source

Thrown at spark/v4.0/spark/src/main/java/org/apache/iceberg/spark/ExtendedParser.java:99

    return null;
  }

  private static ParserInterface getNextDelegateParser(ParserInterface parser) {
    try {
      Class<?> clazz = parser.getClass();
      while (clazz != null) {
        for (Field field : clazz.getDeclaredFields()) {
          field.setAccessible(true);
          Object value = field.get(parser);
          if (value instanceof ParserInterface && value != parser) {
            return (ParserInterface) value;
          }
        }
        clazz = clazz.getSuperclass();
      }
    } catch (Exception e) {
      log().warn("Failed to scan delegate parser in {}: ", parser.getClass().getName(), e);
    }

    return null;
  }

  private static Logger log() {
    return LoggerFactory.getLogger(ExtendedParser.class);
  }

  List<RawOrderField> parseSortOrder(String orderString) throws AnalysisException;
}

View on GitHub (pinned to 86d9c8fc54)

Solutions

1. Align Spark and Iceberg versions (use the connector artifact built for your exact Spark version).
2. Inspect the logged exception to see whether it's NoSuchField/Security/CCE and fix accordingly.
3. If parsing still works via the fallback path, this warning can be tolerated.
4. If extended SQL features fail, file an issue with the Spark/Iceberg version pair.

// Verify version alignment before using extended parser features
String sparkVersion = org.apache.spark.SPARK_VERSION;
Preconditions.checkArgument(sparkVersion.startsWith("4.0"),
    "ExtendedParser requires Spark 4.0.x, found " + sparkVersion);

try {
  ParserInterface p = ExtendedParser.findParser(delegate);
} catch (Exception e) {
  LOG.warn("Falling back to standard parser", e);
}

When it happens

Trigger: Calling findParser/getNextDelegateParser when the wrapped Catalyst parser class layout changed (Spark version mismatch) or a SecurityException/ClassCastException occurs during reflective field scanning.

Common situations: Running an Iceberg build against a newer/older Spark 4.x than it was compiled for, where ParserInterface fields were reshuffled; restricted classloader environments (some app servers) blocking reflection.

Understand the failure class

Background: "is not a compatible type" / "cannot merge" errors: when a value's type doesn't match what the library requires — this error's family across 65 libraries.

Related errors

• Failed to scan delegate parser in {}:
• Cannot parse order: parser is not an Iceberg ExtendedParser
• Cannot convert unsupported type to Spark:
• Unknown manifest content:
• Unsupported manifest type:

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/10a10c100a9ed379. Report an issue: GitHub.