Yesterday we were in the process of applying an update to the kernel for our servers and when we got to the second server (Squid9) it had a kernel panic. This required that we revert back to the previous kernel and reboot that server. This morning we we saw the same issue with the new kernel on Squid8 and we are in the process of reverting it back as well.
Until we have a cause and a fix for the kernel panic we will be holding off updating them to avoid any additional outages.
UPDATE: As a precaution we will be dropping the kernel on all of our servers to a previous version which will require a quick reboot of each server.