Information on unlocking the extra Stash Tab in Diablo Immortal, and what happens when you remove your authentication features

What to do if you receive an error that your code is already claimed in your account.

Troubleshooting for WoW Companion Application crash errors

Troubleshooting steps for problems installing or patching Hearthstone on mobile devices

If you do not have a decryption key, check the installation instructions for a point of contact.

What to do if you cannot access your Hearthstone game progress on a mobile device

Blizzard support cannot assist with this error, please contact Activision Support. 

How a friend can contact Customer Support when she/he can't log in.

If you have a regular version and want to register for the first edition, you need to contact customer support.

What to do if the verification code received via SMS doesn't work