in case you are using additional dkms modules like r8168 you need to install proxmox-headers-6.17 too
so
apt install proxmox-kernel-6.17 proxmox-headers-6.17
tested on my smol - 3x Lenovo Tiny M920q Cluster, with i5-8500T/32GB/512 NVMe and...
EDIT: Resolved :
Post in thread 'Upgrade from Alpha to Beta Fails'
https://forum.proxmox.com/threads/upgrade-from-alpha-to-beta-fails.171763/post-800205
Following the upgrade instructions, I get the following - what is the command to download...