Proxmox VE is using APT as package management system. Updates can be installed via GUI or via CLI. Updating via GUI is introduced with Proxmox VE 3.1. For detailed update instructions see always Downloads.
The list of repositories is defined in /etc/apt/sources.list and or /etc/apt/sources.d/.
Beginning with Proxmox VE 3.1, the default and recommended repository is the Proxmox VE Enterprise Repository (pve-enterprise). To be qualified to access Proxmox VE Enterprise Repository, each of your Proxmox VE Servers need a valid Subscription Key. For more details about Proxmox VE Subscriptions, see http://www.proxmox.com/proxmox-ve/pricing
The pve-no-subscription repo can be used for testing and non-production use. Its not recommended to run on production servers as these packages are not always heavily tested and validated. As the name suggests, there is no Proxmox VE Subscription Key needed to access this repository.
In order to use the pve-no-subscription repository, check and adapt your sources.list (/etc/apt/sources.list):
deb http://repos.uclv.edu.cu/debian wheezy main contrib non-free # security updates deb http://repos.uclv.edu.cu/debian-security wheezy/updates main contrib # PVE packages provided by proxmox.com deb http://repos.uclv.edu.cu/proxmox wheezy pve-no-subscription # #
To prevent error messages accessing the Proxmox VE Enterprise Repository (if you have no Subscription key), you can disable this repo by commenting out the following line:
# nano /etc/apt/sources.list.d/pve-enterprise.list
# deb https://enterprise.proxmox.com/debian wheezy pve-enterprise