This error is seen when updating through a repository or using the
.deb installer. I’m using Ubuntu 20.04.
I found an 2016 post about a similar issue but I’m not sure how relevant it is, or if the debugging command there might work. Unable to update Insync via apt
It seems that the installation went without any problems because I was able to start insync and the current version is 40833.
By running as sudo the postinst script (
/var/lib/dpkg/info/insync.postinst), and adding
set -x to check which line is failing. It seems the error happens when running the
update_key function, something to do with the
apt-key add command. By commenting line 96, I was able to run the postinst script without any errors.