Ubuntu 14.04.3 LTS manually invoked unattended-upgrade fails

[desdan]

I am attempting to manually run the unattended-upgrade for security only updates. I am running 14.04.3 LTS server. I've checked the /etc/apt/apt.conf.d/50unattended-upgrades file to make sure it is set to upgrade only security updates.
When I run 'unattended-upgrade' at the command prompt it pauses (ostensibly because it is trying to download the upgrade), but it eventually reports

An error occurred: '404 Not Found [IP: 2001:67c:1360:8001::17 80]'
The URI 'http://security.ubuntu.com/ubuntu/pool/main/o/openssl/libssl1.0.0_1.0.1f-1ubuntu2.22_amd64.deb' failed to download, aborting


I checked out the URI http://security.ubuntu.com/ubuntu/pool/main/o/openssl/ and found that indeed there is no file by the name of
libssl1.0.0_1.0.1f-1ubuntu2.22_amd64.deb
but there is a file called libssl1.0.0_1.0.1f-1ubuntu2.23_amd64.deb (note the only change is in red)

Assuming I can use the ...2.23_amd64.deb file, how do I tell my system to use that file?If I cannot use that file, where do I point the unattended-upgrade to get the missing file (and how do I set it)?
Thanks

Des

[deadflowr]

You error out because the automatic unattended-upgrades settings run sudo apt-get update first, before attempting to invoke the unattended-upgrade command.
So you need to do that too.

[desdan]

Ah - that makes sense. Thanks - worked as expected.

[mörgæs]

Good, please mark the thread solved.