UPDATE: It turns out, after some testing, that it's a .NET error when launching, hence, the black for the Plutonium launcher. I think I might need a different version of .NET, considering I have .NET 4 and 4.8 installed. Might I need a different version of it?

@Hadi77KSA Hi there this helped me as well but also could you tell me if you are able to connect BO2servers multiplayer? Because for me it says "Black ops2 servers are not available at the moment please try later" Dont know if its network issue or game files issue. It has been happening since the new update

@StormFire451 The moderators and contributors have no power to do anything here.

launch as admin

Your path has invalid/special/non english characters

Which steam deck are you using, the LCD or OLED model?

@Xertu said: LeroyFromBo2 there is no email associated with that account... if it is yours, you'll need to remember the password. Also, make sure you type it in correctly. LeroyFromBo2 is correct leroyfrombo2 is not!

Disable Smart App Control, that fixed it for me.

@Icwithheat hey bro, how do you fix it? i still have the same problem

Probably a network issue Check your firewall/antivirus/DNS or use a VPN Cloudflare WARP or a regular VPN will do for example