Same for me,
After the upgrade, The Qlik desktop is returning a blank screen with the message : Could not Reach ... (-102).
Started the installation again to do a REPAIR (solution proposed in some post) but this didn't solved the issue.
The only way to access Qlik Sense Desktop for me is to use the URL (localhost:4848/hub) in Chrome or Firefox.
Upgrade done today using the version Qlik Sense Desktop 3.1 SR4