Since yesterday after midday (around), no longer able to upgrade or install packages from “Software Center” or yum.
The reason is listed here:
http://centos.muzzy.it/6.6/readme
the solution is to change /var/cache/yum/x86_64/6/centos-base/mirrorlist.txt
replacing 6.6 with 6
bye
Giordy
A lot of updates after I made the modifications (Add / Remove packages work too).
Thank you giordy ! 
Gabriel
You’re welcome 
Happy to help anyone who is working like me in this hot summer
You are welcome, but I didn’t make the updates yet.
What about this (http://centos.muzzy.it/6.6/readme):
"This directory (and version of CentOS) is deprecated. For normal users,
you should use /6/ and not /6.6/ in your path. Please see this FAQ
concerning the CentOS release scheme:
https://wiki.centos.org/FAQ/General
If you know what you are doing, and absolutely want to remain at the 6.6
level, go to http://vault.centos.org/ for packages.
Please keep in mind that 6.0, 6.1, 6.2, 6.3, 6.4 , 6.5 and 6.6 no longer gets any updates, nor any security fix’s."
Maybe Filippo and NS Team can give us more details?
What is the best solution?
Gabriel
centOS release 6.7 when many people are in holiday
this is the problem…
Did you make the updates?
If yes, there are any issues with NetServer till now?
Gabriel
After these updates we will have CentOS 6.7?
Gabriel
I will try to look into it in the afternoon.
We will stay on 6.6 branch until September. We already scheduled the upgrade to 6.7 but we need to do some tests
I think this is a good temporary workaround. 
We’re working on a permanent solution.
I’ll keep you updated.
Yes, and let us know hot it works 
I just changed the script on the server.
Now all NethServer are pointing to vault.centos.org.
This will be changed as soon as tests for CentOS 6.7 are all passed.
Ok!
I will proceed to updates and I will keep you informed how the system works.
Gabriel
Also updated the associated git repo
IMO there’s a “conceptual” bug…
Since there are no higher and medium release changes for daemons in centos’ update (it’a a rh’s policy), we should not care about the upgrades and let the repos point to the last/more updated version…
Otherwise, any time centos guys release a new version, we’ll suffer the same issue.
Moreover, NS works like a sw layer and takes care of generate conf files, so no issues at all should be expected
@zamboni, you describe a perfect world, but it doesn’t exist, we’re all humans and we make mistakes.
I don’t expect problems from 6.7, but I prefer to have controlled testing before breaking all systems. 
in this hot summer as well! (Here In Italy)