Here is the error doing it via CLI
Download suceeded
Checking upgrade image...Done
Preparing to upgrade...Done
Copying upgrade image...Done
Removing old image...Failed to remove old image
admin@ubnt:~$
If I use the Show Version command it only shows 1.9.0
dmin@ubnt:~$ show version
Version: v1.9.0
Build ID: 4901118
Build on: 08/04/16 11:31
Copyright: 2012-2016 Ubiquiti Networks, Inc.
HW model: EdgeRouter Lite 3-Port
HW S/N: 802AA84D0334
Uptime: 09:16:52 up 20:11, 2 users, load average: 0.23, 0.39, 0.23
Show system Image shows the following.
admin@ubnt:~$ show system image
The system currently has the following image(s) installed:
v1.9.0.4901118.160804.1131 (running image) (default boot)