What causes "Clone not supported for " in pentaho/pentaho-kettle?

Add `implements Cloneable` to the offending class (the name is in the exception message)

pentaho/pentaho-kettle · error · IllegalArgumentException

Clone not supported for

Error message

Clone not supported for

What it means

BaseFileErrorHandling.clone() calls super.clone(); if the class (or a subclass) does not implement Cloneable, the JVM throws CloneNotSupportedException, which this code converts into an IllegalArgumentException naming the offending class. This is a programming/invariant error, not expected runtime input.

Solutions

Add `implements Cloneable` to the offending class (the name is in the exception message)
Ensure the default Object.clone() shallow copy is acceptable; deep-clone mutable fields if needed
Alternatively, implement clone() manually without relying on super.clone()

Example fix

// before
class BaseFileErrorHandling { ... }
// after
class BaseFileErrorHandling implements Cloneable { ... }

Defensive patterns

Strategy: try-catch

Validate before calling

if (!(obj instanceof BaseFileErrorHandling && obj instanceof Cloneable)) {
  throw new IllegalArgumentException("Not cloneable: " + obj.getClass().getName());
}

Type guard

boolean isCloneable(Object o) { return o instanceof Cloneable; }

Try / catch

try { copy = errorHandling.clone(); }
catch (IllegalArgumentException e) {
  log.error("Clone unsupported: {}", e.getMessage());
  copy = new BaseFileErrorHandling(); // construct a fresh instance instead
}

Prevention

Always declare `implements Cloneable` when overriding clone()
Deep-copy mutable fields in clone() for custom step subclasses
Unit-test clone() on custom step meta classes

When it happens

Trigger: Subclassing BaseFileErrorHandling (or adding a non-cloneable field type that breaks Cloneable semantics) and having PDI clone the step's error-handling settings object without the class being Cloneable.

Common situations: Custom step development extending base file handling classes but forgetting to implement Cloneable; refactoring that removed Cloneable from the hierarchy.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/2d7f0fa9ed9fdf10. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/file/BaseFileErrorHandling.java:68

  /** The extension of error files */
  @Injection( name = "ERROR_FILES_EXTENTION" )
  public String errorFilesExtension;

  /** The directory that will contain line number files */
  @Injection( name = "LINE_NR_FILES_TARGET_DIR" )
  public String lineNumberFilesDestinationDirectory;

  /** The extension of line number files */
  @Injection( name = "LINE_NR_FILES_EXTENTION" )
  public String lineNumberFilesExtension;

  @Override
  public Object clone() {
    try {
      return super.clone();
    } catch ( CloneNotSupportedException ex ) {
      throw new IllegalArgumentException( "Clone not supported for " + this.getClass().getName() );
    }
  }
}

View on GitHub (pinned to f3058517a1)