Greetings, @UncleSam
I have been experiencing a similar issue since I configured my first i-MSCP installation (on 1.3.8) just a few weeks ago. I have done a fair amount of troubleshooting and finally created my first Bug Tracker case just a couple of hours ago.
The problem occurs for me on Ubuntu LTS Server 14.04.5 “Trusty Tahr.” I have confirmed that does not affect Debian 8.6 “Jessie.” I had not tested Ubuntu LTS 16.04.1 “Xenial Xerus”, so I am pleased to see a possible confirmation from another user on the newer Ubuntu release. This would seem to confirm it is am Ubuntu-specific bug.
If you run a “df -a” do you see duplicate mounts at the end of the list?
While we await a fix, I believe this should provide a workaround to remove extraneous mounts that seem to be causing the failure (if you are seeing the same thing happening for you):
After this, you should be able to clear the “hung” deletion by navigating to the “System Tools/Debugger” page (as Admin) and scrolling to the bottom for the “Pending Tasks” and click “Execute Tasks.” If that doesn’t work, run my “workaround” again and then run an imscp-autoinstall -d
Hope this helps! I am confident that Laurent will have no trouble solving this now that we are closing in on an explanation.
Happy New Year!