Micro Focus Kanaka for Mac 3.0.1 provides backward compatibility for 2.7.x and 2.8.x client components which include the Desktop Client, Plug-in, and Plug-in Console. This means that existing client components do not need to be immediately upgraded when the Kanaka Server component is upgraded.
With Micro Focus Kanaka for Mac 3.0.1, the Kanaka clients validate the certificate being used. This certificate must be trusted by macOS.
2.7 clients will continue to function as-is because they do not perform certificate validation.
However, once you upgrade a client to version 3.0.1, you will need to replace your server.pem with one that is either signed by a well-known CA or ensure that the client is trusting the root certificate that was used to sign your server.pem.
2.8 clients will continue to function as-is because it is assumed that they have already been configured with a trusted root of the CA that signed the existing server.pem used by the 2.8 Kanaka Engine.