Hey there,
Sorry to see you are running into that ABC Error. What platform are you on and how long have you been seeing that error? Also, where exactly are you getting that error and does it stop you from playing the game at all? Have you tried doing a reset of your network by unplugging your modem & router for 45 seconds each? After doing that make sure to do a hard reset of your console or Steam (if you are on PC) as well before trying Black Ops 3 again. Lastly, if you are still running into that error after all of that test your connection to make sure that there isn't anything interfering, like a firewall or anti-virus program. You may be able to improve that connection by opening up ports to Black Ops 3, as described in our Port Forward and NAT FAQ. Take a look at all of that and let me know. Thanks!
-Sean