unable to cleanly complete sudo apt-get upgrade

[tizme]

apt-get upgrade resulting in this message:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following additional packages will be installed:
  libpam-runtime
The following NEW packages will be installed:
  libpam-runtime
0 upgraded, 1 newly installed, 0 to remove and 62 not upgraded.
Need to get 37.9 kB of archives.
After this operation, 307 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://ap-southeast-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 libpam-runtime all 1.1.8-3.2ubuntu2.1 [37.9 kB]
Fetched 37.9 kB in 14s (2,568 B/s)                      
Preconfiguring packages ...
E: Can not write log (Is /dev/pts mounted?) - posix_openpt (2: No such file or directory)
(Reading database ... 14140 files and directories currently installed.)
Preparing to unpack .../libpam-runtime_1.1.8-3.2ubuntu2.1_all.deb ...
Unpacking libpam-runtime (1.1.8-3.2ubuntu2.1) ...
dpkg: error processing archive /var/cache/apt/archives/libpam-runtime_1.1.8-3.2ubuntu2.1_all.deb (--unpack):
 unable to open '/usr/share/man/man7/PAM.7.gz.dpkg-new': No such file or directory
Errors were encountered while processing:
 /var/cache/apt/archives/libpam-runtime_1.1.8-3.2ubuntu2.1_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)