Plutonium

shefsito what is your antivirus? Adding Plutonium and BO2 folder as exclusions could help. Guide here
Also try to run the Redist-Installer just to make sure you have every redist required.

SaFizeV2 Anticheat ban policy that you should have read clearly says that the anticheat is always active in online mode even in solo/custom game so just wait for the unban and follow the instructions next time.

iXA7L Make sure you are in-game when your friend is joining and also make sure nothing is blocking the connection like firewall or antivirus firewall. If this still doesn't work then you either did something wrong when or one of you has something blocking the connection (VPN, firewall etc.)

UnknownEra

• Make sure your game is in windowed borderless, not in fullscreen
• Make sure there are no mods in the Activision mods folder
• If you got this map from a server the files could be broken so if the 2 suggestions above don't work I'd recommend deleting the mod and getting the files yourself instead, at least for this mod. You can download maps from the custom maps recommended websites.

N1ghttyBruh You either have to backup steam_api.dll and put it in the BO2 folder again when you wanna play using Steam (to access campaign) or repair your game in Steam every time you wanna play on Steam again. You could also either have 2 separate BO2 installations or get a small batch script to move the file accordingly. I could create that script for you if you want.

Agustintineo You should try to read a bit before asking for such things, that's a common question already listed in FAQ

@Syhena This is used by both Steam online games developers and pirates to use that "developer sandbox" to fake connection or something to be used for multiplayer on cracked games but it's not always related to piracy, it's a developer stuff that got used by pirates.

stinkie_ Add Plutonium folder and BO2 folder as exclusions in both. Tutorial here
Also repair your game just in case.

stinkie_ what is your antivirus? Even if it is disabled some of them can still cause issues.

Hopirri no one does that what are you even saying? You either have shitty internet that starts lagging at some point, downloads that start at some point in the background or the server you're playing on has issues.

@SayKo_ is there anything you're doing minutes before you crash? Like using alt tab, opening an overlay or something like that?
Also you should upload the crash dump so that staff can take a look at it

@SayKo_ What is your antivirus? (even if it is disabled)
Also you could try to repair your game.

sovagekiller12 This error means you didn't select the folder that contains your BO2 files.
Send a screenshot of your BO2 path in the launcher and another of your BO2 files like this

Bryan5 Just upload the videos to Youtube, Streamable or any legit video sharing website and send the link here (or edit your message)

HTM-RALLY-KIDS You have to make sure the map you got from the internet is the exact same files than the server, if it starts downloading when joining this means they aren't the same files. Also could just be an issue with the server itself

@X-F2 You cheated and tried to evade your ban

HTM-RALLY-KIDS Some servers have broken FastDL causing you to crash on join because the files you got from them are broken. I'd recommend deleting the mod in %localappdata%\Plutonium\storage\t4\mods and installing it yourself by downloading it from a website before joining instead.
Then you could start your game and join that server again and this will skip the FastDL part and use your already installed files instead.

SimpleTexT NutKawaiiDesu Plutonium doesn't give access to the campaign because Plutonium's goal is to add features to the game such as a working anticheat, dedicated servers, modding etc.
Since there is nothing to add to the campaign and since Plutonium's goal isn't piracy we recommend that you buy the game on Steam or on a trusted key site.
https://store.steampowered.com/app/202970/Call_of_Duty_Black_Ops_II/
https://www.instant-gaming.com/en/95-buy-game-steam-call-of-duty-black-ops-ii/

As for multiplayer and zombies make sure you always start them using the launcher. You cannot switch between multiplayer and zombies using the in-game buttons.

The_R34l_Juan Deja de ver los vídeos de mierda no oficiales que no están actualizados o los virus y lee la guía oficial en su lugar. Para instalar Plutonium hay que leer las instrucciones del sitio web de Plutonium.