Cannot remove btsync

[triplemaya]

I spent a fruitless morning trying to get btsyc to work, and installed and uninstalled many times trying out btsync-gui / btsync-user / btsync-user-gtk etc.
Now I cannot uninstall it. Error is:

Traceback (most recent call last): File "/usr/lib/linuxmint/mintinstall/AptClient/AptClient.py", line 80, in _run cache.commit(acquire_progress_monitor, install_progress_monitor) File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 508, in commit raise SystemError("installArchives() failed") SystemError: installArchives() failed

And now every time I do an update the system tries to install btsync-user and fails.

Error is:

Select all (synaptic:16036): GLib-CRITICAL **: g_child_watch_add_full: assertion 'pid > 0' failed (Reading database ... 198729 files and directories currently installed.) Preparing to unpack .../btsync-user_1.16.0-1_all.deb ... Unpacking btsync-user (1.16.0-1) over (1.16.0-1) ... dpkg: error processing archive /var/cache/apt/archives/btsync-user_1.16.0-1_all.deb (--unpack): trying to overwrite '/usr/bin/btsync', which is also in package btsync 2.3.8-1 postrm called with unknown argumentabort-upgrade'
dpkg: error while cleaning up:
subprocess new post-removal script returned error exit status 1`

I have searched here and on google for " unknown argument abort-upgrade" but the results I get seem to me to be dealing with quite low level stuff and I don't want to start experimenting when I have no idea what I am doing. At the moment the system still works! (This seemed like a good decision when I found this comment on the forum in one of the posts: Unfortunately the whole debian package system depends on the installation scripts never failing. )