pentaho/pentaho-kettle · error

The function call isFolder throw an error :

Error message

The function call isFolder throw an error : 

What it means

isFolder() resolves its argument via KettleVFS to a FileObject and tests whether it is a folder. If a java.io.IOException occurs while resolving or reading the VFS object (the underlying filesystem layer fails), the function rethrows it as a JavaScript runtime error prefixed 'The function call isFolder throw an error : '. This is an I/O-layer failure, distinct from the argument-validation error of the same function.

Solutions

1. Verify the path is a valid, fully-qualified VFS URI (correct scheme, escaped special characters)
2. Check the target filesystem (network share/SFTP server) is reachable and credentials are correct
3. Run the path through a simpler call like isFile() to isolate whether VFS resolution itself fails
4. Upgrade/align commons-vfs and provider libraries if the scheme is genuinely supported

Example fix

// before
var isDir = isFolder('/data/ reports');  // space breaks URI parsing
// after
var isDir = isFolder('file:///data/%20reports'); // or sanitize the path

// pre-check reachability in script
var f = isFile(path); // returns false or throws per type; existence errors surface here

function isProbablyVfsUri(v) { return typeof v === 'string' && /^[a-z]+:\/\//.test(v); }

try { var d = isFolder(path); } catch (e) {
  // e contains 'isFolder throw an error : <IOException>' — treat as unavailable
  d = false; }

When it happens

Trigger: KettleVFS.getFileObject(path) or file.exists()/getType() throws IOException — e.g. an unsupported or malformed VFS URI scheme, network filesystem unreachable, permission/lock issues during resolution, or closing errors on the underlying resource.

Common situations: Wrong URI scheme (missing sftp://, s3:// prefix) so VFS picks the wrong provider; an SFTP/SMB/network share that is down or unreachable; a path string containing characters that break URI parsing; VFS provider (jsch/commons-vfs) version problems.

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

• Error opening new file
• The function call getFileExtension throw an error :
• The function call getLastModifiedTime throw an error :
• The function call getParentFoldername throw an error :
• The function call getShortFilename throw an error :

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/a44969a83b4e2ec2. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/scriptvalues_mod/ScriptValuesAddedFunctions.java:2281

        }
        FileObject file = null;

        try {
          // Source file
          file = KettleVFS.getInstance( getBowl( actualObject ) ).getFileObject( Context.toString( ArgList[0] ) );
          boolean isafolder = false;
          if ( file.exists() ) {
            if ( file.getType().equals( FileType.FOLDER ) ) {
              isafolder = true;
            } else {
              Context.reportRuntimeError( "[" + Context.toString( ArgList[0] ) + "] is not a folder!" );
            }
          } else {
            Context.reportRuntimeError( "folder [" + Context.toString( ArgList[0] ) + "] can not be found!" );
          }
          return isafolder;
        } catch ( IOException e ) {
          throw Context.reportRuntimeError( "The function call isFolder throw an error : " + e.toString() );
        } finally {
          if ( file != null ) {
            try {
              file.close();
            } catch ( Exception e ) {
              // Ignore errors
            }
          }
        }

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

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