pentaho/pentaho-kettle · error · KettleException

Can't create object

Error message

Can't create object 

What it means

BeanInjector.createObject() uses reflection to instantiate a nested object along the injection path, either via a no-arg constructor or a single-arg constructor taking the root. Any reflective failure (no accessible constructor, instantiation exception) is wrapped in this KettleException.

Solutions

1. Add a public no-arg constructor to the nested class
2. Add a constructor taking the root bean type if contextual construction is needed
3. Make the injected property type concrete (not abstract/interface)
4. Catch-and-log to see the wrapped cause for why newInstance failed

Example fix

// before
class Child { Child(Root r, int extra){...} } // no matching ctor
// after
class Child { public Child(){} public Child(Root r){...} }

// Verify the nested class has a usable constructor before injecting
Class<?> c = nestedPropertyType;
boolean ok = Arrays.stream(c.getConstructors()).anyMatch(ctor ->
  ctor.getParameterCount() == 0
  || (ctor.getParameterCount() == 1 && ctor.getParameterTypes()[0].isAssignableFrom(rootClass)));
if (!ok) throw new IllegalStateException("No injectable constructor on " + c.getName());

static boolean instantiableForInjection(Class<?> c, Class<?> root) {
  if (c.isInterface() || Modifier.isAbstract(c.getModifiers())) return false;
  try { c.getDeclaredConstructor(); return true; }
  catch (NoSuchMethodException e) {
    for (Constructor<?> k : c.getConstructors())
      if (k.getParameterCount() == 1 && k.getParameterTypes()[0].isAssignableFrom(root)) return true;
    return false;
  }
}

try {
  injector.injectValue(bean, path, value);
} catch (KettleException e) {
  if (e.getMessage().startsWith("Can't create object")) {
    log.error("Failed to instantiate nested bean; cause: ", e.getCause());
  } else throw e;
}

When it happens

Trigger: setProperty encounters a path level whose class lacks a usable no-arg constructor or a constructor accepting the root object; constructor throws during newInstance.

Common situations: Nested bean without a default constructor; abstract class or interface in the injection path; constructor throws IllegalArgumentException on root.

Related errors

• Constructor not found for
• DefaultAuthenticationConsumerFactory.Constructor
• DefaultAuthenticationConsumerFactory.Constructor.Arg
• No field or getter defined for
• No field or setter defined for

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/d806e14178075cbc. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/core/injection/bean/BeanInjector.java:340

          throw new KettleException( "No field or setter defined for " + root.getClass() );
        }
      }
    }
    return true;
  }

  private Object createObject( Class<?> clazz, Object root ) throws KettleException {
    try {
      // Object can be inner of metadata class. In this case constructor will require parameter
      for ( Constructor<?> c : clazz.getConstructors() ) {
        if ( c.getParameterTypes().length == 0 ) {
          return clazz.newInstance();
        } else if ( c.getParameterTypes().length == 1 && c.getParameterTypes()[0].isAssignableFrom( info.clazz ) ) {
          return c.newInstance( root );
        }
      }
    } catch ( Throwable ex ) {
      throw new KettleException( "Can't create object " + clazz, ex );
    }
    throw new KettleException( "Constructor not found for " + clazz );
  }

  private Object extendArray( BeanLevelInfo s, Object obj, int newSize ) throws Exception {
    Object existArray = s.field.get( obj );
    if ( existArray == null ) {
      existArray = Array.newInstance( s.leafClass, newSize );
      s.field.set( obj, existArray );
    }
    int existSize = Array.getLength( existArray );
    if ( existSize < newSize ) {
      Object newSized = Array.newInstance( s.leafClass, newSize );
      System.arraycopy( existArray, 0, newSized, 0, existSize );
      existArray = newSized;
      s.field.set( obj, existArray );
    }

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