CA PPM will trap on underlying http status codes that are unexpected (for example: "0") instead of the usual codes of "200", "302", etc...
If there is a network disconnect or SSO timeout, or other connection interruption between the client and the server, the web browser will throw an XHR exception with an http status code of "0".
The popup will then display to the user. This is to let the user know that something went wrong and to try again.
To address the issue, reference the <CAPPM_HOME>/logs/app-ca.log at the time the user received the popup.
An error will appear with the username of the user that saw the issue:
OnError called--Client Side Exception
java.lang.Exception: VXMLRequest failed. HTTP status code was: 0
One common cause can be Load Balancer (for example: F5 Networks load balancer) or Apache Web Server - Reverse Proxy server in front of the PPM application server.
Configuration here can cause connections to timeout or become interrupted.