pentaho/pentaho-kettle · error · RuntimeException

The function call isFolder throw an error : + e.toString()

Error message

The function call isFolder throw an error :  + e.toString()

What it means

This is the IOException handler of ScriptAddedFunctions.isFolder(): any failure while resolving or reading the VFS FileObject (KettleVFS.getFileObject or file.exists()/getType()) is re-thrown as RuntimeException with the prefix 'The function call isFolder throw an error : ' followed by e.toString(). It signals an I/O-level problem (not a logical 'folder missing' condition) while accessing the path.

Solutions

  1. Read the appended e.toString() to identify the underlying IOException cause (connection refused, unknown host, malformed URI, etc.).
  2. Validate the VFS URL format/scheme and encode special characters in the path before calling.
  3. Test connectivity/credentials to the remote filesystem; retry once connectivity is restored.
  4. Run the step with more verbose logging or catch the RuntimeException in the JavaScript step to inspect the message.
  5. Fix root cause rather than swallowing: e.g. correct the VFS provider configuration.

Example fix

// before
var ok = isFolder( someUserUrl ); // may throw: The function call isFolder throw an error : ...
// after
try {
  var ok = isFolder( encodeURI( someUserUrl ) );
} catch ( ex ) {
  Logger.logError( "isFolder IO problem: " + ex.message );
}
Defensive patterns

Strategy: try-catch

Validate before calling

// validate the VFS URL shape before calling
if ( /^[a-z]+:\/\//.test(p) || p.indexOf("/") === 0 ) { /* plausible path */ }

Type guard

function isValidVfsPath(p) { return typeof p === "string" && p.trim().length > 0 && !/["<>|]/.test(p); }

Try / catch

try { ok = isFolder(p); } catch (e) { var m = String(e.message); if (m.indexOf("throw an error") >= 0) { Logger.logError("VFS IO: " + m); /* retry or fail row */ } }

Prevention

When it happens

Trigger: Calling isFolder(path) when KettleVFS.getFileObject or exists()/getType() throws IOException — unreachable remote host, invalid URI/scheme, network interruption, or filesystem permission/IO errors.

Common situations: Malformed VFS URLs (bad scheme like 'file:/path with spaces' unescaped); SFTP/HTTP VFS servers down or credentials changed; network partitions during a long-running transformation; disk errors.

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

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/25974453d2fdf269. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/trans/steps/script/ScriptAddedFunctions.java:2192

        }
        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 {
        throw new RuntimeException( "The function call isFolder is not valid." );
      }
    } catch ( Exception e ) {
      throw new RuntimeException( e.toString() );
    }
  }

View on GitHub (pinned to f3058517a1)