Comment 27 for bug 1522675

In case useful, I have just done a fresh install of Xenial, followed by 'sudo apt-get install synaptic'. The following error arose when trying to install blubuntu-theme and blubuntu-wallpapers
W: Can't drop privileges for downloading as file '/root/.synaptic/tmp//tmp_sh' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied).
After completely removing via synaptic, it installed fine with apt-get.