Czesc Justyna, thanks a lot. Hard to say from outside, but the Python error logs would be helpful. The Cloud Function should return the error to the Workflow as well, so check the Logs in GCP.

That being said, the Cloud Function (Python) part is not designed to work for SFTP, only for "normal" FTP. For SFTP, you'd need to extend the Cloud Function a bit. For SFTP, I use the paramiko library usually - hope that helps a bit.