It means the Dashboard requires an updated version of the Plex Web client.
The Plex Web client is updated on a regular basis.
The version that was included with your PMS download will not be the most recent version.
The most recent version is always available at https://app.plex.tv/desktop.
You can follow the Plex Web thread to be notified when new releases are available. Scroll to the bottom of the thread, click on “Normal” and change it to “Watching.”
