I still use Debian Squeeze, and since this release has been archived (Feb 29, 2016) I use the archives repositories on archive.debian.org
deb http://archive.debian.org/debian-archive/debian/ squeeze main contrib non-free
deb http://archive.debian.org/debian-archive/debian/ squeeze-lts main contrib non-free
Since 2 days , I get this error message with aptitude update: (same with apt-get)
E: Release file expired, ignoring http://archive.debian.org/debian/dists/squeeze-lts/Release (invalid since 2d 17h 24 min 57s)
With increasing time of course. I tried many other archives repositories but same error. I found this workaround:
aptitude -o Acquire::Check-Valid-Until=false update
It works, but I would find a solution without this option. I have no fast possibility to update aptitude parameters on all servers I'm running.
By the way the question is: what is the problem with repositories ? Am I doing something wrong ?
I found no update or news about repositories problem on Debian site/mailing list.
Create a file with setting:
echo 'Acquire::Check-Valid-Until "false";' >/etc/apt/apt.conf.d/90ignore-release-date
The release-files of the repository have an expire date (Valid-until).
See the part in the documentation: https://wiki.debian.org/RepositoryFormat#Date.2CValid-Until