apache/hadoop · error · UnsupportedOperationException

Unbound ${method}

Error message

Unbound ${method}

What it means

DynamicWrappedIO binds seven static methods of org.apache.hadoop.io.wrappedio.WrappedIO reflectively via DynMethods (bulkDelete_delete, bulkDelete_pageSize, fileSystem_openFile, pathCapabilities_hasPathCapability, streamCapabilities_hasCapability, byteBufferPositionedReadable_readFullyAvailable, byteBufferPositionedReadable_readFully). requireAllMethodsAvailable() throws UnsupportedOperationException("Unbound " + method) when any binding is null — meaning the WrappedIO class was found but does not contain that exact static method with the expected signature (or was not found at all, leaving every method unbound).

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/wrappedio/impl/DynamicWrappedIO.java:239

  /**
   * For testing: verify that all methods were found.
   * @throws UnsupportedOperationException if the method was not found.
   */
  void requireAllMethodsAvailable()  throws UnsupportedOperationException {

    final DynMethods.UnboundMethod[] methods = {
        bulkDeleteDeleteMethod,
        bulkDeletePageSizeMethod,
        fileSystemOpenFileMethod,
        pathCapabilitiesHasPathCapabilityMethod,
        streamCapabilitiesHasCapabilityMethod,
        byteBufferPositionedReadableReadFullyAvailableMethod,
        byteBufferPositionedReadableReadFullyMethod,
    };
    for (DynMethods.UnboundMethod method : methods) {
      LOG.info("Checking method {}", method);
      if (!available(method)) {
        throw new UnsupportedOperationException("Unbound " + method);
      }
    }
  }


  /**
   * Are the bulk delete methods available?
   * @return true if the methods were found.
   */
  public boolean bulkDelete_available() {
    return available(bulkDeleteDeleteMethod);
  }

  /**
   * Get the maximum number of objects/files to delete in a single request.
   * @param fileSystem filesystem
   * @param path path to delete under.
   * @return a number greater than or equal to zero.

View on GitHub (pinned to 2add963021)

Solutions

1. Align hadoop-common versions across the classpath: inspect with mvn dependency:tree or dump java.classpath and remove/upgrade the stray older hadoop-common jar.
2. At startup check DynamicWrappedIO.loaded() and the per-API probes (bulkDelete_available(), etc.) instead of assuming all methods are bound.
3. If you vendored a copy of DynamicWrappedIO, update the method-name constants and signatures to match the WrappedIO version actually on your classpath.
4. Look for shaded/duplicate org.apache.hadoop classes (jar tf | grep 'wrappedio/WrappedIO') and keep exactly one version.

Example fix

// before
new DynamicWrappedIO().requireAllMethodsAvailable(); // UnsupportedOperationException: Unbound ... after hadoop-common downgrade

// after
DynamicWrappedIO dio = new DynamicWrappedIO();
if (!dio.loaded() || !dio.bulkDelete_available()) {
  LOG.warn("WrappedIO incomplete on classpath; falling back to non-vectored path");
} else {
  // safe to use the dynamic bindings
}

DynamicWrappedIO dio = new DynamicWrappedIO();
if (!dio.loaded()) {
  throw new IllegalStateException("WrappedIO class missing from classpath");
}
if (!dio.bulkDelete_available()) {
  LOG.warn("bulkDelete unbound: hadoop-common version mismatch");
}

try {
  dyn.requireAllMethodsAvailable();
} catch (UnsupportedOperationException e) {
  // name the unbound method; audit classpath for duplicate/old hadoop-common jars
  LOG.error("WrappedIO binding incomplete: {}", e.getMessage());
}

When it happens

Trigger: Instantiating DynamicWrappedIO against a hadoop-common jar older or newer than the WrappedIO API this class expects (method renamed, added, or signature changed); the WrappedIO class absent from the classpath (loadClass returns null so all loadStaticMethod calls yield unbound methods); duplicate/shaded copies of hadoop-common where an older WrappedIO wins classloading; invoking requireAllMethodsAvailable() in tests after a version bump.

Common situations: Version drift between hadoop-common artifacts on one classpath; third-party stores copying DynamicWrappedIO into their codebase (the 'copy-and-paste adoption' the loaded flag mentions); dependency shading pinning an older hadoop-common; upgrading Hadoop in a project that vendors this adapter.

Related errors

• Cannot initialize the class: {clazz}
• "Unknown protocol: " + protocolName
• Error creating plugin: {}
• Unknown channel mode: {}
• Cannot find method: {name}

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/1d32183ed8276525. Report an issue: GitHub.