Setup Closes During Upgrade (7.5 to 7.7.1)

We are upgrading our LDSD system from version 7.5 to 7.7.1. Running setup.exe on the Service Desk server will return the error below. Why is this so? Take note that Service Desk server was setup by another admin previously (7.5) and not by me. Does it matter? If yes, what fix to apply?

We are seeing this error.

Problem signature:

  Problem Event Name:                        CLR20r3

  Problem Signature 01:                       setup.exe

  Problem Signature 02:                       9.1.0.0

  Problem Signature 03:                       533365ec

  Problem Signature 04:                       LANDesk.Install.ServiceDesk.UI

  Problem Signature 05:                       1.0.0.0

  Problem Signature 06:                       533365f7

  Problem Signature 07:                       1ed

  Problem Signature 08:                       13b

  Problem Signature 09:                       System.NullReferenceException

  OS Version:                                          6.1.7601.2.1.0.272.7

  Locale ID:                                             1033

  Additional Information 1:                  af4e

  Additional Information 2:                  af4ef5396516c93ca9a84c60399a50c5

  Additional Information 3:                  b04f

  Additional Information 4:                  b04fdbeb287d2de687d5c77cf83e2561