What does Error Code 100 on Diablo 4 mean?

The short answer

Error code 100 in Diablo 4 means the game lost its connection to Blizzard’s servers or couldn’t connect in the first place.

Why does it happen?

Diablo 4 requires a constant internet connection to play, even solo. Error code 100 shows up when that connection breaks. The most common causes are:

  • Blizzard’s servers are down — during maintenance windows, major patches, or high-traffic periods like new season launches, the servers can become overloaded or go offline
  • Your internet connection dropped — even a brief interruption can kick you out since the game needs a stable connection at all times
  • Firewall or antivirus blocking the game — security software can sometimes prevent Diablo 4 from reaching Blizzard’s servers
  • DNS or network configuration issues — outdated DNS settings or a congested local network can interfere with the connection

How to fix it

Try these steps in order:

  1. Check Blizzard’s server status — visit Blizzard’s support page or their social media accounts to see if servers are down for everyone
  2. Restart the game and launcher — close Diablo 4 and the Battle.net launcher completely, then reopen them
  3. Restart your router — unplug it for 30 seconds, plug it back in, and wait for it to fully reconnect
  4. Switch to a wired connection — if you’re on Wi-Fi, a direct ethernet cable gives you a more stable connection
  5. Flush your DNS — on Windows, open Command Prompt and run ipconfig /flushdns to clear stale network data
  6. Disable VPN or proxy — these can interfere with the game’s ability to reach Blizzard’s servers
  7. Check your firewall — make sure Diablo 4 and Battle.net are both allowed through your firewall and antivirus

When should you worry?

Most of the time, this error is temporary.

  • If Blizzard’s servers are down, there’s nothing to do but wait. These outages usually resolve within a few hours
  • If it only happens to you, the problem is likely on your end and the steps above should fix it
  • If it keeps coming back, your internet connection may be unstable. Contact your internet provider if you notice frequent drops in other apps too