When you try to install Update Rollup 2 for Microsoft Exchange Server 2010 Service Pack 3 (KB2866475), you receive the following error message:
The feature you are trying to use is on a network resource that is unavailable.
Click OK to try again, or enter an alternate path to a folder containing the installation package 'ExchangeServer.msi' in the box below.
Click OK to try again, or enter an alternate path to a folder containing the installation package 'ExchangeServer.msi' in the box below.