What causes "Unable to close output of file '${filename}'" in pentaho/pentaho-kettle?

Check the wrapped cause via getException()/getCause() to identify the filesystem error.

pentaho/pentaho-kettle · error · KettleException

Unable to close output of file

Error message

Unable to close output of file '${filename}'

What it means

FileLoggingEventListener.close() closes the VFS output stream opened in the constructor. If outputStream.close() throws (disk full, file deleted/locked mid-write, filesystem failure), the IOException is wrapped in a KettleException with the filename. Callers such as Trans/Job execute() invoke this when stopping file logging.

Solutions

Check the wrapped cause via getException()/getCause() to identify the filesystem error.
Verify the log target filesystem was available and writable for the whole run (use local disk where possible).
Ensure close() is called once, in a finally block, and not concurrently from multiple threads.
Increase disk space / remove disk-full conditions on the log volume.

Example fix

// before
listener.close(); // may throw KettleException
// after
try {
  listener.close();
} catch (KettleException e) {
  log.logError("Failed closing log file", e.getCause() != null ? e.getCause() : e);
}

Defensive patterns

Strategy: try-catch

Validate before calling

// Verify target still writable before long runs
File f = new File(filename);
if (!f.getParentFile().canWrite()) throw new IllegalStateException("Log dir not writable");

Try / catch

try {
  listener.close();
} catch (KettleException e) {
  Throwable root = e.getCause() != null ? e.getCause() : e;
  log.logError("Failed to close log file '" + filename + "': " + root.getMessage(), root);
} finally {
  KettleLogStore.getAppender().removeLoggingEventListener(listener);
}

Prevention

Log to local disk rather than volatile network mounts.
Call close() exactly once from a finally block; the listener tracks its own exception via getException().
Monitor disk space on the log volume.
Don't delete or rotate the log file externally while the job runs.

When it happens

Trigger: Calling close() (directly or via job/trans execute paths) after the underlying VFS file handle became invalid or the filesystem errors during close — e.g. disk full, file removed externally, network share dropped.

Common situations: Long-running jobs writing logs to a network mount that disconnects; cleanup tooling deleting the log file while the transformation runs; container filesystem issues.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/ac7755cdaf7d621b. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/core/logging/FileLoggingEventListener.java:112

        if ( logToFile ) {
          String logText = layout.format( event );
          outputStream.write( logText.getBytes() );
          outputStream.write( Const.CR.getBytes() );
        }
      }
    } catch ( Exception e ) {
      exception = new KettleException( "Unable to write to logging event to file '" + filename + "'", e );
    }
  }

  public void close() throws KettleException {
    try {
      if ( outputStream != null ) {
        outputStream.close();
      }
    } catch ( Exception e ) {
      throw new KettleException( "Unable to close output of file '" + filename + "'", e );
    }
  }

  public KettleException getException() {
    return exception;
  }

  public void setException( KettleException exception ) {
    this.exception = exception;
  }

  public String getFilename() {
    return filename;
  }

  public void setFilename( String filename ) {
    this.filename = filename;
  }

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