PlayStation Network is down as Memorial Day weekend beginsTime: May. 31, 2018 From: SCDKey
Recently, you may find it difficult to access some games on your PlayStation 4 because the Play Station Network is not available during the weekend of Memorial Day in the United States.
Social network players complain about connection errors in the PSN service. This prevents players from accessing online multiplayer services and other games that require connection to a third-party server. You will also have trouble opening a party and connecting with your friends in other ways.
Sony has also confirmed the error on its website.
The PSN status page says that"You may have some difficulty launching games, applications, or online features", "Our engineers are working to resolve the issue as soon as possible, and we thank you for your patience".
However, this may not have the same effect on everyone, so if you log in, try not to reboot the system or log off.