pentaho/pentaho-kettle · error · RuntimeException

[ + ArgList[0] + ] is not a folder!

Error message

[ + ArgList[0] + ] is not a folder!

What it means

Thrown by ScriptAddedFunctions.isFolder() when the VFS object at ArgList[0] exists but its FileType is not FileType.FOLDER — i.e. the caller passed a regular file where a directory was expected. The function resolves the path via KettleVFS, confirms it exists, then validates the type; a file (or other non-folder type) fails the check and aborts with this RuntimeException.

Solutions

1. Check the path with isFile()/ls and confirm whether it is a file; remove or rename the file if the directory was intended.
2. Correct the path passed to isFolder() to point at an actual directory (add the missing path segment or trailing name).
3. If the path may be either, branch in the script: if(isFile(p)) {...} else if(isFolder(p)) {...}.
4. Create the intended directory first (mkdir) if it does not exist and the file is unrelated.
5. Validate the path ends at a directory before calling, e.g. via Java Files.isDirectory() or a KettleVFS type check.

Example fix

// before
var ok = isFolder( "/data/report.txt" ); // throws: [/data/report.txt] is not a folder!
// after
var ok = isFolder( "/data/reports" ); // existing directory

// before calling
var f = getFileSize(p); // or isFile(p); confirm p points to a directory before isFolder(p)

function looksLikeDirectory(p) { return typeof p === "string" && !/\.[A-Za-z0-9]+$/.test(p); }

try { ok = isFolder(p); } catch (e) { if (String(e.message).indexOf("not a folder") >= 0) { /* handle file-instead-of-folder */ } else { throw e; } }

When it happens

Trigger: Calling isFolder(path) from a JavaScript step with a path that resolves to an existing regular file (e.g. /data/report.txt) instead of a directory.

Common situations: Typos dropping the trailing directory name so the path points at a file; config fields where the user entered a file path in a 'folder' input; VFS symlinks or name collisions where a file was created where a folder was expected.

Related errors

• folder [ + ArgList[0] + ] can not be found!
• Error opening new file
• failed to check isFile in setPath()
• GPG.ErrorCheckingGPGFile
• JobGetMailsFromPOP.Error.AttachmentFolderNotAFolder

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/f704894cd9fd5d75. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/script/ScriptAddedFunctions.java:2185

  public static boolean isFolder( Bowl bowl, ScriptEngine actualContext, Bindings actualObject, Object[] ArgList,
    Object 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( bowl ).getFileObject( (String) ArgList[0] );
          boolean isafolder = false;
          if ( file.exists() ) {
            if ( file.getType().equals( FileType.FOLDER ) ) {
              isafolder = true;
            } else {
              throw new RuntimeException( "[" + ArgList[0] + "] is not a folder!" );
            }
          } else {
            throw new RuntimeException( "folder [" + ArgList[0] + "] can not be found!" );
          }
          return isafolder;
        } catch ( IOException e ) {
          throw new RuntimeException( "The function call isFolder throw an error : " + e.toString() );
        } finally {
          if ( file != null ) {
            try {
              file.close();
            } catch ( Exception e ) {
              // Ignore errors
            }
          }
        }

      } else {

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