Setup Wizard for Exchange Update Rollup ended prematurely

The issue is well-known, but I never got around to share it myself and just recently saw it once again at a customer, who experienced the problem.
This blog post will cover how to install and the Exchange Rollup Update successfully without getting the “Ended prematurely” error.
The Setup Wizard for Update Rollup fails with the error “ended prematurely”. It has been the same issue for Update Rollups for both Exchange 2007 and Exchange 2010.
The installer fails with the information:

Setup Wizard for Update Rollup 5 for Exchange Server 2010 Service Pack 3 (KB2917508) ended prematurely because of an error. Your system has not been modified. To install this program at a later time, please run the installation again.

The screen dump below also shows what error look like:

The reason for the error and why the Update Rollup installer is “ended prematurely” is because the server has User Access Control (UAC) activated on the server. For good reason, it is not recommended to disable the UAC.
The error is also shown in the event log, as Event ID: 1024 and with error code 1603.

How to Install the Update Rollup

The recommended process for installing Update Rollups on the server, is using an elevated command prompt (Open a CMD with Run As Administrator) and make sure the Update Rollup is located on a local drive of the server and start the installer using:
SYNTAX example: msiexec /update <UPDATE .MSP FILE>
How to Start Setup Wizard:

msiexec /update Exchange2010-KB2917508-x64-en.msp

How to install the Update Rollup unattended (silent) add the following parameter (/quiet):

msiexec /update Exchange2010-KB2917508-x64-en.msp /quiet

Example as elevated command prompt starting the Update Rollup installer:

This will start the Setup Wizard and you can now walk your way through the installer and install the Update Rollup and when it has been installed, you should see the following:

Other reasons for failing

The above is the most obvious reason for why the Update Rollup fails with “ended prematurely”, but if you see error codes 1603 or 1635 in the event log, there could be other reasons.