#0 - Sept. 26, 2010, 12:56 a.m.
Similarly, in order to access the World of Warcraft: Cataclysm beta, you will need to install and then patch the latest beta client. If your account is flagged for the Cataclysm beta, you can download the installer via Battle.net: https://us.battle.net/account/management/wow/cataclysm-beta-download.html
These clients cannot be used interchangeably, and attempting to log into the PTR using the beta client (and vice-versa) will result in an error. Please ensure that you have the appropriate patched clients installed and are using the correct client when logging in. Thanks!