Using Smart Upgrade to upgrade from 6.5.4 to 8.0.2. NOTE: Works fine for 8.0.1. Smart Upgrade.
During installation, after Notes closes and it spins for about 5 minutes, I get the error:
Error 1311.Source file not found:
C:\Windows\Installer\Data1.cab. Verify that the file exists and that you can access it.
Have rebooted and also ran the installation manually and it worked just fine… only fails through Smart Upgrade. I did check C:\Windows and there isn’t an Installer directory (which is probably why it’s erroring out - but why?).
Using the following syntax for the file:
802ClientOnly-standard.exe
With the following arguments:
-s -a /s /v"/qb+! SELECTINSTALLFEATURES=SametimeUI"
Again, same as the 8.0.1 which works perfectly. The Smart Upgrade document is correct.
I’ve proved the download isn’t corrupt (works on manual install) and that a reboot won’t help 
Any thoughts or advice would be appreciated.