These errors can be caused by temporary server issues in a specific region.

Troubleshooting steps for disconnections in StarCraft II

Troubleshooting steps for Diablo II (2000) crash errors

Information on error BLZ51900001

Information on error BLZ51901021

The game cannot log in due to corrupted cache data in the Users/Shared/Blizzard directory, or the directory's permissions are preventing the game from accessing the Users/Shared/Blizzard directory.

ゲームクライアントの言語設定をデフォルトに戻すには、以下の手順に従ってください。

Battle.net携帯通知に関する情報

Information on unlooted items and The Postmaster.

Troubleshooting steps for resolving network problems in World of Warcraft.