Comment 17 for bug 729288

cache.log, attached, shows nothing odd AFAICS, normal shutdown. dist-upgrade failed,

    Preparing to replace squid 2.7.STABLE9-2ubuntu5.1 (using .../squid_2.7.STABLE9-2ubuntu5.2_amd64.deb) ...
    Unpacking replacement squid ...
    Processing triggers for ureadahead ...
    ureadahead will be reprofiled on next reboot
    Processing triggers for ufw ...
    Processing triggers for man-db ...
    Setting up squid-common (2.7.STABLE9-2ubuntu5.2) ...
    Setting up squid (2.7.STABLE9-2ubuntu5.2) ...
    restart: Job failed to restart
    dpkg: error processing squid (--configure):
     subprocess installed post-installation script returned error exit status 1
    Errors were encountered while processing:
     squid
    E: Sub-process /usr/bin/dpkg returned an error code (1)
    $

After finding this bug report I tried

    $ sudo status squid
    squid stop/waiting
    $ sudo start squid
    squid start/running, process 11334
    $ sudo status squid
    squid start/running, process 11334

which is 12:43:30 in the log file. It appears to be working fine now.