Watch the video:
Timestamps:
0:00 - Explanation
0:12 - What to try first 
0:19 - Check server status
0:46 - Link Activision & Blizzard
1:16 - Wireless users
1:29 - Close all other programs
1:46 - Try a VPNThe Black Ops: Cold War Umbrella Merge Conflict Error is a common error that’s relatively easy to fix. This video takes you through some troubleshooting steps to try and get the game back to a working state. Hopefully, by the end of it, the game is playable as expected.
Check server status: https://support.activision.com/onlineservices
Check account link: https://s.activision.com/activision/login
EVERY SETTING BENCHMARKED: Go to post or View on YouTube
Other Black Ops: Cold War videos:
- [NEW] Fix Fatal Errorr 3107840166 + More: Go to post or View on YouTube
 - BEST Optimization guide: Go to post or View on YouTube
 - BETA: Fix Random Crashes: Go to post or View on YouTube
 - Change Activision Name: Go to post or View on YouTube
 - Fix “Cannot Connect to Online Services”: Go to post or View on YouTube
 - Fix “Lobby, not Joinable”: Go to post or View on YouTube
 - Fix Blurry Vision In-Game: Go to post or View on YouTube
 - Fix Fatal Error 3107840166: Go to post or View on YouTube
 - Fix Fatal Error Guide: Go to post or View on YouTube
 - Fix High CPU Usage: Go to post or View on YouTube
 - Fix Infinite Shader Install: Go to post or View on YouTube
 - Fix Infinite loading screens: Go to post or View on YouTube
 - Fix Lag/Improve connection: Go to post or View on YouTube
 - Fix Lost Connection to Host: Go to post or View on YouTube
 - Fix Stutter, Drops & Stabilize FPS: Go to post or View on YouTube
 - Fix Umbrella Merge Conflict: Go to post or View on YouTube
 - HD Texture Pack Benchmark: Go to post or View on YouTube
 - Lower VRAM Usage: Go to post or View on YouTube
 - OPEN NAT [Port Forwarding]: Go to post or View on YouTube
 - Skip intro: Go to post or View on YouTube