probably a stupid question, but if i want to change my raspberry to an upgraded model, do i have to reinstall all or just switch the sd card to the new?!
i have octoprint on a raspberry 3 model b and now i would love to switch to the 4..
Depends on the OctoPi version you used. OctoPi 0.17 supports most Raspberry Pi 4s, but some of them refuse to boot. In which case you will need to flash 0.18.
The built in backup/restore makes this quite painless though, if you do have to reflash.
the only Pi4 with issues will be the Pi4 8G version.
Before you remove the sd card from the old pi, make sure you ssh in and run "sudo apt update && sudo apt full-upgrade -y && rpi-update" hit enter then reboot when done. pull the SD card out and put it in the pi4 and off you go. The updates load the latest bootloader to the SD card so it will be compatible with the Pi4
And the new rev 1.4 boards for all, 2GB and 4GB as well
That's why there's a large warning on https://octoprint.org/download, along the lines of