Players of the Black Ops 1 port on PS5 are encountering persistent problems joining online Zombies matches. Attempts to connect repeatedly fail, often resulting in players being placed alone in private lobbies. The error message "Unable to join game session in progress" appears, indicating a matchmaking or server-side issue specific to Zombies mode. Other multiplayer modes on PS5 remain unaffected, isolating the problem to Zombies gameplay. This disruption affects fans seeking cooperative play and has sparked community calls for a timely fix as of July 2026.
- Issue affects only Zombies mode on PS5 Black Ops 1 port.
- Error message: "Unable to join game session in progress."