pentaho/pentaho-kettle · error · KettleValueException

TO_CHAR Couldn't convert Date to String

Error message

TO_CHAR Couldn't convert Date to String 

What it means

Thrown when the legacy Value dat2str/TO_CHAR function's SimpleDateFormat.format() call fails while formatting the current date value (arg0 = format pattern, arg1 = DateFormatSymbols pattern chars). The value is first reset to a null String, then the underlying exception is chained into this KettleValueException — typically an invalid SimpleDateFormat pattern or an inaccessible date value.

Solutions

1. Correct the TO_CHAR date format pattern (arg0) so it is a valid SimpleDateFormat pattern
2. Remove or fix the DateFormatSymbols pattern characters passed as arg1
3. Ensure the input value actually holds a valid Date before calling TO_CHAR

When it happens

Trigger: Thrown at core/src/main/java/org/pentaho/di/compatibility/Value.java:3116 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/2cfb2303c112b5d5. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/compatibility/Value.java:3116

    if ( isNull() ) {
      setType( VALUE_TYPE_STRING );
    } else {
      if ( getType() == VALUE_TYPE_DATE ) {
        SimpleDateFormat df = new SimpleDateFormat();

        DateFormatSymbols dfs = new DateFormatSymbols();
        if ( arg1 != null ) {
          dfs.setLocalPatternChars( arg1 );
        }
        if ( arg0 != null ) {
          df.applyPattern( arg0 );
        }
        try {
          setValue( df.format( getDate() ) );
        } catch ( Exception e ) {
          setType( VALUE_TYPE_STRING );
          setNull();
          throw new KettleValueException( "TO_CHAR Couldn't convert Date to String " + e.toString() );
        }
      } else {
        throw new KettleValueException( "Function DAT2STR only works on a date" );
      }
    }

    return this;
  }

  // implement the TO_DATE function, arguments in args[]
  public Value num2dat() throws KettleValueException {
    if ( isNull() ) {
      setType( VALUE_TYPE_DATE );
    } else {
      if ( isNumeric() ) {
        setValue( new Date( getInteger() ) );
        setLength( -1, -1 );
      } else {

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