Service Packs and Updates Packages for UAG are not cumulative so in order to get to the latest build you’ll need to install each individually. The order of installation should be as described:
UAG-KB2585140 – UAG Service Pack 1 Update 1
TMG-KB2555840 – TMG Service Pack 2
TMG-KB2689195 – TMG Rollup 2 for TMG SP2
TMG-KB980674 – TMG Array Hotfix
UAG-KB2710791 – UAG Service Pack 2
UAG-KB2744025 – UAG Service Pack 3
In any case the installations of UAG service packs fail due to a premature error, be sure you are running the installers as administrators. The second thing to do is enable verbose logging during the installation.
The error is because the schema upgrade operations are timing out. To extend, temporarily increase the value by modifying the machine.config file located within C:\Windows\Microsoft.NET\Framework64\v2.0.050727\CONFIG by adding the following element just before the </configuration> tag. Re-run the service pack to install.
Reference KB2811066 for fix.