Re: Stretch to Buster
Like was mentioned before, do the backups with "win32diskimage" before you start, but you shouldn't have to format the micro SD card, just copy to another SD card and it will be copied exact.
I also had pretty good luck with the link off Tom's Hardware as Aaron suggested:
doing the "In Place Upgrade"
The command that they mention works better than some instructions that I found on another site:
grep -rl stretch /etc/apt/ | sudo xargs sed -i 's/stretch/buster/g'
This replaces ALL the instances of "stretch" with "buster", which caused me some headaches.
A previous site suggested updating the firmware on the R-Pi, but in doing some digging, I found that that was NOT recommended because you could load a beta version onto your Pi and brick it!
Especially, because I was using a friend's Pi 3B, I didn't do it.
That site was:
The other command is nice in that it combines two commands:
sudo apt update && sudo apt dist-upgrade
the "update" and the "apt dist-upgrade". (I'm an old Unix programmer, some of this actually makes sense to me!)
As you go through the upgrade, there will be a few questions about upgrading some if the existing apps.
As I recall, I'm pretty sure I answered "Y" to pretty much all of them. (They don't make a lot of sense to any one but the programmer that wrote the code!)
The command that Arron mentioned:
"sudo apt purge timidity ..." etc.
will actually remove a number of apps that are not supported by the R-Pi.
You should also run the command:
sudo apt autoremove -y
This will clean up some of the leftover files from the upgrade.
The second time I ran it, it took much less time than the first. About 4 hours, vs 8 hours the first time around (plus some errors, the first time!)
Worked much better on my R-Pi 4B when I followed the suggestions on Tom's Hardware site.
I haven't tried ALL of the functions on the Pi, but so far, so good!