Skip to main content

This content has been archived and is no longer being updated. Links may not function; however, this content may be relevant to outdated versions of the product.

Support Article

SFTP Test connectivity fails with PPK



SFTP connection using PPK file fails.

Error Messages

Status: Fail
Message: Unable to connect

Caused by:
com.jcraft.jsch.JSchException: Session.connect: Prime size must be multiple of 64, and can only range from 256 to 2048 (inclusive) at com.jcraft.jsch.Session.connect(

Steps to Reproduce

  1. Create an FTP Server rule with a KeyStore file.
  2. Customize the Data-Admin-Security-KeyStore.Validate activity to suppress the PPK validation.
  3. Click Test Connectivity.

Root Cause

A defect or configuration issue in the operating environment.
The default SFTP server port is 22; however the server was customized to a different port number.


As a local-change, modify the SFTP port number to the default port number.

Published April 29, 2018 - Updated October 8, 2020

Was this useful?

0% found this useful

Have a question? Get answers now.

Visit the Collaboration Center to ask questions, engage in discussions, share ideas, and help others.

Did you find this content helpful?

Want to help us improve this content?

We'd prefer it if you saw us at our best.

Pega Community has detected you are using a browser which may prevent you from experiencing the site as intended. To improve your experience, please update your browser.

Close Deprecation Notice
Contact us