apache/iceberg · error · NoSuchFunctionException

Function does not exist:

Error message

Function does not exist: 

What it means

SupportsFunctions.loadFunction resolves a function name against the Iceberg-side registry (SparkFunctions); when no registered UnboundFunction matches the given identifier, it throws NoSuchFunctionException. This happens when Spark hands Iceberg an identifier it cannot resolve to a known Iceberg-implemented function.

Solutions

1. Check the function name spelling against SparkFunctions registered names
2. Upgrade the Iceberg Spark runtime jar to a version that registers the function
3. Verify the function is an Iceberg-supported function rather than a Spark built-in
4. Register a custom function implementation if the function is user-defined

Example fix

// before
SELECT iceberg_years(ts) FROM t; // NoSuchFunctionException
// after
SELECT years(ts) FROM t; // use the registered name, or upgrade Iceberg

boolean known = SparkFunctions.load(name) != null; // or check registered function list before invoking

boolean isSupportedFunction(String name) { return SparkFunctions.load(name) != null; }

try { ... } catch (NoSuchFunctionException e) { LOG.error("Unknown function {}", name, e); throw e; }

When it happens

Trigger: Calling a function in SQL that Spark delegates to Iceberg (e.g. via a catalog that extends SupportsFunctions) where the name is misspelled, not registered in SparkFunctions, or only exists in a newer Iceberg version than the one on the classpath.

Common situations: Version skew between Spark extension jar and function availability (function added in a later Iceberg release); typos in function names; calling an Iceberg-specific function without the Spark functions registry loaded.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Cannot load function
• Already closed files for partition:
• ALTER TABLE contains multiple distribution clauses
• ALTER TABLE contains multiple distribution clauses
• ALTER TABLE contains multiple distribution clauses

AI-assisted analysis of apache/iceberg@86d9c8fc54 (2026-09-12). Data as JSON: /api/errors/dd464dbab93da083. Report an issue: GitHub.

Appendix: source

Thrown at spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/SupportsFunctions.java:63

      return new Identifier[0];
    }

    throw new NoSuchNamespaceException(namespace);
  }

  @Override
  default UnboundFunction loadFunction(Identifier ident) throws NoSuchFunctionException {
    String[] namespace = ident.namespace();
    String name = ident.name();

    if (isFunctionNamespace(namespace)) {
      UnboundFunction func = SparkFunctions.load(name);
      if (func != null) {
        return func;
      }
    }

    throw new NoSuchFunctionException(ident);
  }
}

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