Attempting to upgrade x86_64 Fedora 35 to 36, and it fails almost immediately with the error:
Problem: The operation would result in removing the following protected packages: kernel-core
I googled quite a bit, and the only common advice to resolve this is ensure that installonly_limit in /etc/dnf/dnf.conf is greater than 1. But its set to 3 in my case.
Temporarily change /etc/dnf/dnf.conf to install_limit=0 which means dnf should never auto remove kernels.
The only kernel* that would be protected is the kernel your booted into when dnf wants to update the kernel* and you’ve run out of open slots.
Setting install_limit=0 gives you unlimited open slots.