Altered Windows hosts files may prevent game client installation, or cause issues with patching. The hosts file is a Windows system file that can override DNS and redirect URLs or IP addresses to different locations. A typical home internet user will not have a modified hosts file.

Checking for Modifications

  1. Press Windows Key + R.
  2. Type %WinDir%\System32\Drivers\Etc into the Run window and click OK.
  3. Open the hosts file with a text editor such as Notepad. Hosts will not have a file extension.
  4. Compare your hosts file with the Microsoft defaults listed below. If yours is different, it has been modified. Remove any lines that contain Blizzard URLs or addresses.
  5. Save the file.

Note: If your hosts file was modified, run a virus scan. Viruses and malware can modify the hosts file to try to redirect your computer to malicious websites.

Common Problematic Modifications

These modifications negatively affect Blizzard games. If you find them, remove them:


Resetting the Hosts File to Microsoft Defaults

To reset the Hosts file back to the default, follow these steps:

  1. Press Windows Key + R.
  2. Type notepad into the Run window.
  3. Click OK.
  4. Copy the following text to the Notepad window:
    # Copyright (c) 1993-2006 Microsoft Corp.
    # This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
    # This file contains the mappings of IP addresses to host names. Each
    # entry should be kept on an individual line. The IP address should
    # be placed in the first column followed by the corresponding host name.
    # The IP address and the host name should be separated by at least one
    # space.
    # Additionally, comments (such as these) may be inserted on individual
    # lines or following the machine name denoted by a '#' symbol.
    # For example:
    # # source server
    # # x client host
    # localhost name resolution is handle within DNS itself.
    # localhost
    # ::1 localhost
  5. On the File menu, select Save as, type "hosts" (including the quotation marks) in the File name box, and then save the file to the desktop.
  6. Press Windows Key + R again.
  7. Type %WinDir%\System32\Drivers\Etc into the Run window and click OK.
  8. Rename the Hosts file to "Hosts.old".
  9. Copy or move the Hosts file that you created from your desktop to the %WinDir%\System32\Drivers\Etc folder. If you are prompted to enter an administrator password, select Continue.