pentaho/pentaho-kettle · error

The function call isFile is not valid.

Error message

The function call isFile is not valid.

What it means

isFile() is a JavaScript scripting function added by PDI (Kettle)'s ScriptValuesMod step. It resolves its single argument to a VFS FileObject and reports whether it is a regular file. Before doing any I/O it validates the JavaScript argument list; if the call does not have exactly one non-null, non-undefined argument it throws 'The function call isFile is not valid.' via Context.reportRuntimeError, which surfaces as a JavaScript runtime error inside the transform.

Solutions

1. Ensure isFile is called with exactly one argument, e.g. isFile(filename)
2. Check the argument variable is defined and not null/undefined before calling (use JS typeof / null checks or a 'If field value is null' step)
3. Correct upstream field mappings so the filename field is populated
4. Wrap the call in try/catch inside the script to handle bad input gracefully

Example fix

// before
var ok = isFile();
// after
var path = 'file:///data/input.csv';
var ok = isFile(path);

// in the JS step, before calling
if (typeof myFile === 'undefined' || myFile === null) {
  throw new Error('myFile must be a non-null path string');
}
var result = isFile(myFile);

function isNonEmptyString(v) { return typeof v === 'string' && v.length > 0; }

try { var ok = isFile(path); } catch (e) { // log and continue row
  ok = false; }

When it happens

Trigger: Calling isFile() with zero arguments, more than one argument, or with an argument that is JavaScript null or undefined (e.g. a field variable that was never populated). The guard is `ArgList.length == 1 && !isNull(ArgList[0]) && !isUndefined(ArgList[0])`.

Common situations: A typo in the variable name inside a JavaScript step (the variable is undefined), a field upstream that did not produce a value, copy-pasted sample code calling isFile with a missing parameter, or passing the result of another function that returned undefined.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• The function call dateAdd requires 3 arguments.
• The function call dateDiff requires 3 arguments.
• The function call fillString requires 2 arguments.
• The function call fireToDB requires 2 arguments.
• The function call getFileExtension is not valid.

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/d11f6ec7b8acab7b. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/scriptvalues_mod/ScriptValuesAddedFunctions.java:2250

            }
          } else {
            Context.reportRuntimeError( "file [" + Context.toString( ArgList[0] ) + "] can not be found!" );
          }
          return isafile;
        } catch ( IOException e ) {
          throw Context.reportRuntimeError( "The function call is File throw an error : " + e.toString() );
        } finally {
          if ( file != null ) {
            try {
              file.close();
            } catch ( Exception e ) {
              // Ignore errors
            }
          }
        }

      } else {
        throw Context.reportRuntimeError( "The function call isFile is not valid." );
      }
    } catch ( Exception e ) {
      throw Context.reportRuntimeError( e.toString() );
    }
  }

  public static boolean isFolder( Context actualContext, Scriptable actualObject, Object[] ArgList,
    Function FunctionContext ) {
    try {
      if ( ArgList.length == 1 && !isNull( ArgList[0] ) && !isUndefined( ArgList[0] ) ) {
        if ( ArgList[0].equals( null ) ) {
          return false;
        }
        FileObject file = null;

        try {
          // Source file
          file = KettleVFS.getInstance( getBowl( actualObject ) ).getFileObject( Context.toString( ArgList[0] ) );

View on GitHub (pinned to f3058517a1)