In System - Upgrade - Prepare for Upgrade, upload mub file stuck in "0% Preparing Local Files" for a long time
NSX 4.2.X
Two causes might contribute to the issue:
SSH'ing to it either with the root user, or with the 'admin' user and then switching to the root user by entering the command 'st en'.
If expired, it will show warnings to change the pasword.
In Security section, click "Unblock" next to "This file came from another computer and might be blocked to help protect this computer."