This error is usually caused by an unstable internet connection or a third-party program that is blocking access.

Failed to download a required update. Please check your internet connection and try again.

Troubleshooting steps for disconnection problems with the Battle.net mobile app

Unexpected Blizzard Update Agent errors.

You have attempted to connect to an invalid server. If this problem persists, please contact Customer Support.

Information on error BLZBNTBGS00000026

Information on Error BLZBNTAGT00001399

Information on error BLZBNTBNA00001389

This error means the Battle.net Agent (the process that installs and patches our games) couldn't stream necessary files.

Troubleshooting steps for linking a Twitch.tv account with a Battle.net account.