While editing, saving or refreshing a workflow, the following error is displayed in the web browser:
An error occurred communicating with the server
This error can be caused by a variety of network issues. To get more details turn on your web browser's developer tools (F12 in Chrome) and recreate the error. You should see the URL traffic and if any requests are failing. You can then look at the access logs on the application server (JBoss, Wildfly, Websphere or Weblogic) for clues.
If your organization is using a Single Sign-On system which forces all web traffic through an access management system, such as IBM Tivoli Access Manager (TAM), it's access control list (ACL) may have rules blocking the requests. Look at that systems access logs or use tcpdump to capture the network traffic. If the requests are failing at this server, get the administrator involved to verify the configuration. Rules are often setup where the SSO username's group access control lists restrict access to certain URL or HTTP actions GET, PUT or POST.