I'm getting these same warnings, both for root and regular user, so i found this bug report.
>In my system, both dirs' permissions are 700 and owned by _apt:root, >it doesn't emit any error and changelog works fine, no warnings. Anyway on my system (Debian stretch/testing, aptitude 0.7.4-2): $ ls -ld /var/lib/apt/lists/partial /var/cache/apt/archives/partial drwx------ 2 _apt root 4096 dic 14 10:00 /var/cache/apt/archives/partial drwx------ 2 _apt root 4096 dic 14 09:58 /var/lib/apt/lists/partial
