Comment 7 for bug 1621845

Same on my side:

# sudo apt autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 340 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up redmine (3.2.1-2) ...
Determining localhost credentials from /etc/mysql/debian.cnf: succeeded.
chown: cannot access '/var/lib/redmine/Gemfile.lock': No such file or directory
dpkg: error processing package redmine (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 redmine
Sub-process /usr/bin/dpkg returned an error code (1)

# lsb_release -a; uname -a;
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.2 LTS
Release: 18.04
Codename: bionic
Linux redmine 4.15.0-1036-gcp #38-Ubuntu SMP Mon Jun 24 13:49:05 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Solution found here (https://stackoverflow.com/questions/45757459/redmine-3-2-1-2-ob-ubuntu-16-04-breaks-on-apt-upgrade), was to comment out line 12 of script /var/lib/dpkg/info/redmine.postinst:

#chown www-data:www-data /var/lib/redmine/Gemfile.lock