pentaho/pentaho-kettle · error · KettleFileException

Exception reading line using NIO:

Error message

Exception reading line using NIO:

What it means

FixedInput.readOneRow catches any exception while reading/parsing one fixed-width line via NIO and rethrows it as a KettleFileException with this message plus e.toString(). It indicates the NIO file read or line conversion failed mid-processing, not a field mapping issue.

Solutions

  1. Fix the step's line length / buffer size settings so fileSize is an exact multiple of the line size
  2. Check the chained exception for I/O vs decode errors and repair the source file (CRLF issues, truncation)
  3. Re-transfer the file in binary mode and verify expected file size
  4. Open the file in the step's preview to confirm the layout matches before running the full transformation

Example fix

// before
fileSize = file.length(); // may include trailing partial line
// after
long lines = file.length() / lineLength;
fileSize = lines * lineLength; // ignore trailing partial bytes
Defensive patterns

Strategy: validation

Validate before calling

// validate file before running the transformation
long size = new File( filename ).length();
if ( lineLength <= 0 || size % lineLength != 0 ) {
  throw new IllegalStateException( "File size " + size + " not a multiple of line length " + lineLength );
}

Try / catch

try {
  trans.execute( null );
} catch ( KettleException e ) {
  if ( e.getMessage().startsWith( "Exception reading line using NIO" ) ) {
    // fix file/line-length config and retry
  }
}

Prevention

When it happens

Trigger: Reading a fixed-width file whose byte size is not a multiple of the line length, an I/O error on the underlying channel, or charset/decode errors during ByteBuffer-to-string conversion in processRow.

Common situations: Files transferred in text mode with altered line endings or trailing partial lines; wrong 'line length' setting in the Fixed file input step so the buffer math breaks; file truncated or locked by another process.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/94d945adda6dfdc5. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/fixedinput/FixedInput.java:228

        // CR + Line feed in the worst case.
        //
        if ( data.byteBuffer[data.startBuffer] == '\n' || data.byteBuffer[data.startBuffer] == '\r' ) {

          data.startBuffer++;

          if ( data.byteBuffer[data.startBuffer] == '\n' || data.byteBuffer[data.startBuffer] == '\r' ) {

            data.startBuffer++;
          }
        }
        data.endBuffer = data.startBuffer;
      }

      incrementLinesInput();
      return outputRowData;
    } catch ( Exception e ) {
      throw new KettleFileException( "Exception reading line using NIO: " + e.toString(), e );
    }

  }

  private FileInputStream getFileInputStream( URL url ) throws FileNotFoundException {
    return new FileInputStream( FileUtils.toFile( url ) );
  }

  public boolean init( StepMetaInterface smi, StepDataInterface sdi ) {
    meta = (FixedInputMeta) smi;
    data = (FixedInputData) sdi;

    if ( super.init( smi, sdi ) ) {
      try {
        data.preferredBufferSize = Integer.parseInt( environmentSubstitute( meta.getBufferSize() ) );
        data.lineWidth = Integer.parseInt( environmentSubstitute( meta.getLineWidth() ) );
        data.filename = environmentSubstitute( meta.getFilename() );

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