NEVER start the upgrade process without a valid backup and without testing the same in a test lab setup.
If you run a customized installation and/or you installed additional packages, for example for sheepdog, or any other third party packages, you need to make sure that you also upgrade these package to Debian Stretch.
Again, make sure that you have a valid backup of all CT and VM before you start.
First make sure that your actual installation has the latest package of the Proxmox VE 4.4 release: This action will consume some time - depending on the systems performance, this can take up to 60 min or even more.
There is, however, another way to check: To check for a carrier settings update on your i Phone, open the Settings app and tap General - About.If you feel confortable with the command line, and all your VMs/CTs are one shared storage you can also follow the procedure Bypassing backup and restore when upgrading In-place upgrades are done with apt-get, so make sure that you are familiar with apt before you start here.Tip: You can perform a test upgrade and a standalone server first.Install the Proxmox VE 4.4 ISO on testing hardware, then upgrade this installation to the latest minor version of Proxmox VE 4.4 (see Package repositories), copy/create relevant configurations to the test machine to replicate your production setup as closely as possible. You can even install Proxmox VE 4.4 in a VM and test the upgrade in this environment.All has to be done on each Proxmox VE node's command line (via console or ssh; preferably via console in order to exclude interrupted ssh connections).Proxmox VE 5.x introduces major new features, therefore the upgrade must be carefully planned and tested.Depending on your existing configuration, several manual steps are required, including some downtime.Generally speaking there are two possibilities to move from 4.x to 5.x In both cases you'd better empty the browser's cache after upgrade and reload the GUI page or there is the possibility that you see a lot of glitches.If you run a PVE 4 cluster it's tested and supported to add a PVE 5 node and migrate your guests to the new host.If you run on SSD, the dist-upgrade can be finished in 5 minutes.Start with this step to get the initial set of upgraded packages.If you’re unsure whether or not the carrier settings actually updated, do this: Your carrier settings are up to date and next time you’ll know what it means when i Phone says “Carrier Settings Update”.I’d love to hear from you in the comments section below, and don’t forget to follow Payette Forward on social media platforms for the best i Phone content on the internet!You turn on your i Phone and immediately see a pop-up that reads, “Carrier Settings Update”.