When running Cascade CMS 8.0 or below, the following error message may appear when attempting to publish via SFTP:

SFTP error occurred during SFTP Shuttle initialization: Algorithm negotiation fail

This message indicates that the target web server does not support the diffie-hellman-group1-sha1 key exchange method (typically if OpenSSH on the web server is upgraded to version 6.7+).

There are 3 options for resolving this:

  1. Re-enable the disabled algorithm (diffie-hellman-group1-sha1) on your web server.
  2. Upgrade the SFTP library within Cascade CMS to a more recent version which supports the latest exchange algorithms. To do so, follow these steps:
  • Download the latest JSCH .jar file
  • Stop Cascade CMS
  • Back up the existing jsch-0.1.42.jar in tomcat/webapps/ROOT/WEB-INF/lib and then replace it with the new one
  • Start Cascade

3. Upgrade to Cascade 8.0.1 (or higher). Newer versions of Cascade CMS have an updated SFTP library that includes support for the latest key exchange methods. 

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