Because installation of Rollup 5-v2 for Exchange 2010 SP2 sometimes can be painful, we present list of tips how to install RU5 for Microsoft Exchange 2010 SP2.
First read KB 2785908
Don’t use WSUS to install Rollup 5. Just download it manually from Microsoft Download Center.
Before installation of Rollup 5-v2 make sure you don’t have installed KB2506146 and KB2506143. Uninstall them.
Backup your customized Outlook Web App files. Rolllup will updates the Outlook Web App files if they are required and any customizations of logon.aspx file will be overwritten.
When you install this update RU5 on computer without internet connection, you may experience long installation times. To install fast clear the Check for publisher’s certificate revocation in the Security section of Internet Option (IE).
if you have deployed CAS-CAS proxying,please apply the update rollup on the Internet-facing Client Access servers before you apply the update rollup on the non-Internet-facing Client Access servers