base-passwd install fails during 16.04 upgrade

[Alfred]

Description: Ubuntu 16.04.1 LTS
Release: 16.04
While upgrading from 14.04 lts to 16.04 lts, I got an error (from /var/log/dist-upgrade/apt-term.log):

Writing passwd-file to /etc/passwd
Writing shadow-file to /etc/shadow
Writing group-file to /etc/group
Error writing group-entry: Invalid argument
dpkg: error processing package base-passwd (--configure):
 subprocess installed post-installation script returned error exit status 4
Errors were encountered while processing:
 base-passwd

When I try to install the package manually using "apt-get install base-passwd":

After this operation, 10.2 kB disk space will be freed.
Setting up base-passwd (3.5.39) ...
Removing group "apple" (99)
1 changes have been made, rewriting files
Writing passwd-file to /etc/passwd
Writing shadow-file to /etc/shadow
Writing group-file to /etc/group
Error writing group-entry: Invalid argument
dpkg: error processing package base-passwd (--configure):
 subprocess installed post-installation script returned error exit status 4
Errors were encountered while processing:
 base-passwd
E: Sub-process /usr/bin/dpkg returned an error code (1)

I apologize ahead of time since I'm new to this. I already tried to search for this problem but could not find it.
Thank you.

[Alfred (alcogon)]

Sorry about this, I removed the offending group and that took care of it.

[Alfred (alcogon)]

Group information may have been corrupted so removed group.