After every mission the game would crash and the popup says "unhandled exeption caught". The problem is caused by the career record. I've tried fixing the game's DirectX, changed the windows compatibility mode, and validating files hasn't worked either.

There are 2 ways to fix this problem

-Have 60 friends or less on steam, you've got to clean out your friends list

~OR~

-Disable Black Ops II from accessing the internet

This can be done by turning off your computer's internet, or by disabling the program's internet access in windows firewall

To remove the game's internet access, go to Control Panel > System and Security > Windows Defender Firewall > Advanced settings > Outbound Rules > Actions > New Rule > Select Program > This program path - Browse > Locate your local bo2 folder and select "t6sp.exe" > Block the connection > Domain, Private, Public should already be selected > Name the rule > Finish

When you boot up the game, the singleplayer won't crash and will work normally