Backup is out of date

Hi, in my redundancy application (ignition 7.8.3) I have a master that occupied 11GB of RAM and the communication with the client is interrupted. The server is online and not switch to stand by server.
I restarted the master server and appear on the client the popup with Master is not available, but the backup server is out of date. What do you mean?

Thank’s

Does the backup server have the same modules installed?

Yes, the backup server has the same module installed.