Issues upgrading to 2.3.5 - and solution
Posting this here in case this could be useful to someone
I had a heck of a time upgrading to 2.3.5 and it took me about 12 hrs straight. My advice for the future, is make sure people can always type when they get "mountroot" pop up, even in the case of corrupted fstab files or dirty filestystems. Also, I suggest for the initial screen that has the prompt where you can do "help index" to have a full-fledged shell option. That way, we can manually mount things, fsck, and such.
The first issue I ran into was this kernel panic:
Solved by removing the wireless card
The second issue was a corrupt fstab file. I ran fsck using fsck -c /etc/fstab.old and then I was finally able to remount / rw and copied /etc/fstab.old to /etc/fstab
First, I had the aforementioned kernel panic.
After removing the wireless card, it booted up and seemed to start setting things up. However, after a long time, I couldn't connect from a computer. So eventually I reset the system.
That's when things got ugly. I got a mountroot screen, but I couldn't press any buttons on the keyboard. It's like the system completely locked up.
I couldn't get around this, and tried all the bios settings recommended in the guide. I tried using an install thumb drive to boot, but alas the mobo is too old for that (2002-ish MSI) and for some reason I didn't have a good burnable cdrom laying around (actually, I did but they were all scratched up and that turned out to burn corruptly)...
Eventually I got lucky and did "set mount_cdrom=1" from the initial menu and then it went into mountroot after saying it couldn't load the cdrom. Then I could type! From there, I could manually choose the drive /dev/d1dsd1a or what-not. After a few tries I realized that only got me in read-only, but at least I could get to the shell.
So in the shell, I tried doing "mount -o rw ..." to force it back to rw, but it said it wasn't clean. I had to run fsck -c /etc/fstab.old
Then after fixing it, I could "mount -o rw /dev/yadayada /" and then replace fstab with /etc/fstab.old my original fstab
I couldn't just do a fresh install because I have so many settings, and would need to access the backup made during install. So if that hadn't worked I would have had to install freebsd on another box and manually mount the drive with an old IDE USB enclosure because all my newer computers are SATA.