Similar to in the 17.1 guide, we need to add that upgrades of the following environment types are not supported:

• Standalone
• Single Controller

As described in the above links, both of these environment types are used for proof-of-concept, development, and test scenarios.

The upgrade process is designed to maintain data plane uptime throughout the process and this is not possible for the above environments. It is recommended that these types of environments are re-deployed on the newer release.