apache/iceberg · warning

Failed to scan delegate parser in {}:

Error message

Failed to scan delegate parser in {}: 

What it means

A logged warning emitted when the extended Spark SQL parser cannot reflectively scan a delegate parser to extract its ParserInterface. The code walks the class hierarchy of Spark's parser looking for a delegate field; if reflection fails or an unexpected parser shape is present, the exception is caught, logged, and null is returned, so Spark SQL falls back to the default parser. It indicates the Spark/Iceberg version pairing exposes an internal parser layout this shim does not understand.

Source

Thrown at spark/v4.2/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. Use an Iceberg Spark connector built for your exact Spark version (e.g., iceberg-spark-runtime-4.2 with Spark 4.2).
2. Check the exception in the log for IllegalAccessException/NoSuchFieldException to confirm the reflection mismatch.
3. Remove or align custom parser plugins/SQL extensions that alter the parser delegate chain.
4. Upgrade the Iceberg connector to a release that supports your Spark version's internal parser layout.
5. If SQL extensions are not needed, disable spark.sql.extensions to avoid the code path entirely.

Example fix

// before
-- mismatched jars
spark.jars.packages org.apache.iceberg:iceberg-spark-runtime-4.1_2.13:1.6.0  // on Spark 4.2
// after
spark.jars.packages org.apache.iceberg:iceberg-spark-runtime-4.2_2.13:<matching-version>

// ensure Spark version matches the connector artifact version
assert spark.version().startsWith("4.2"); // when using iceberg-spark-runtime-4.2

// behavior already falls back to the default parser; only investigate if SQL extensions misbehave

When it happens

Trigger: Calling findParser/getNextDelegateParser when Spark's SparkSqlParser internals changed such that the expected delegate field is absent or inaccessible — usually after a Spark patch or major version change incompatible with the Iceberg connector.

Common situations: Mixing an Iceberg spark-runtime built for one Spark version with a different Spark distribution; Spark internal refactoring of ParserInterface delegates; custom SQL parser plugins that wrap the parser differently.

Understand the failure class

Background: "is deprecated and will be removed" — deprecation warnings for old API names, keywords, and options, and how to migrate before the removal release — this error's family across 29 libraries.

Related errors

• Failed to scan delegate parser in {}:
• Failed to scan delegate parser in {}:
• Cannot parse order: parser is not an Iceberg ExtendedParser
• Cannot parse order: parser is not an Iceberg ExtendedParser
• Cannot parse order: parser is not an Iceberg ExtendedParser

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/a50b808a5a27175c. Report an issue: GitHub.