I’m getting this after installing Insync Debian Stretch.
the postinst maintainer script of the package insync seems to use apt-key (provided by apt) without depending on gnupg or gnupg2. This will BREAK in the future and should be fixed by the package maintainer(s).
Note: Check first if apt-key functionality is needed at all - it probably isn’t!
Warning: apt-key should not be used in scripts (called from postinst maintainerscript of the package insync)
Executing: /tmp/apt-key-gpghome.HQTMAHJy40/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys ACCAF35C
gpg: key A684470CACCAF35C: “Insynchq Inc firstname.lastname@example.org” not changed
gpg: Total number processed: 1
gpg: unchanged: 1
sysctl: permission denied on key ‘fs.inotify.max_user_watches’
dpkg: error processing package insync (–configure):
subprocess installed post-installation script returned error exit status 255
Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)