pentaho/pentaho-kettle · error · ParseException

Unknown date format. Format is null.

Error message

Unknown date format. Format is null. 

What it means

DateDetector.getDateFromStringByFormat parses a date string with a caller-supplied format using a non-lenient SimpleDateFormat. If the dateFormat argument is null, a ParseException 'Unknown date format. Format is null.' is thrown immediately, because a null pattern cannot construct a formatter.

Solutions

1. Null-check the format before calling; fall back to detectDateFormat or a default pattern
2. Hard-code or validate the expected format string at configuration time
3. Use getDateFromString (auto-detect) when format is unknown instead of passing null

Example fix

// before
Date d = DateDetector.getDateFromStringByFormat(s, maybeNullFormat);
// after
if (maybeNullFormat == null) { maybeNullFormat = DateDetector.detectDateFormat(s); }
Date d = DateDetector.getDateFromStringByFormat(s, maybeNullFormat);

if (dateFormat == null) { dateFormat = "yyyy-MM-dd"; } // or resolve via detectDateFormat
if (dateString == null) { throw new IllegalArgumentException("dateString required"); }

try {
  return DateDetector.getDateFromStringByFormat(s, fmt);
} catch (ParseException e) {
  LOG.error("Bad format '{}' or value '{}'", fmt, s, e);
  throw e;
}

When it happens

Trigger: Passing a null format, typically the result of detectDateFormat returning null that was forwarded without checking, or a config variable that failed to resolve.

Common situations: Chaining detectDateFormat() -> getDateFromStringByFormat() without a null check; date format read from missing properties/settings.

Related errors

• Unknown date string. Date string is null.
• Could not apply local format for
• Could not apply the given format " + sArg2 + " on the…
• TO_DATE Couldn't convert String to Date
• <toString()> : couldn't convert string

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/594b92852f2a4673. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/core/util/DateDetector.java:242

    if ( dateFormat == null ) {
      throw new ParseException( "Unknown date format.", 0 );
    }
    return getDateFromStringByFormat( dateString, dateFormat );
  }

  /**
   * 
   * @param dateString
   *          date string for parse
   * @param dateFormat
   *          format which should be applied for string
   * @return {@link java.util.Date} converted from dateString by format
   * @throws ParseException
   *           if we can not parse date string
   */
  public static Date getDateFromStringByFormat( String dateString, String dateFormat ) throws ParseException {
    if ( dateFormat == null ) {
      throw new ParseException( "Unknown date format. Format is null. ", 0 );
    }
    if ( dateString == null ) {
      throw new ParseException( "Unknown date string. Date string is null. ", 0 );
    }
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat( dateFormat );
    simpleDateFormat.setLenient( false ); // Don't automatically convert invalid date.
    return simpleDateFormat.parse( dateString );
  }

  /**
   * 
   * @param dateString
   *          - date string for detect date format
   * @return {@link java.lang.String} string which represented Date Format or null
   * 
   */
  public static String detectDateFormat( String dateString ) {
    return detectDateFormat( dateString, null );

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