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If I upgrade the OS to buster on an OS disk (SD card or USB stick) on my pi 3, will it work if I boot a pi 4 off that?

  • 1
    it should - it won't hurt to try – Jaromanda X Jun 30 at 23:31
  • The Foundation advice is to do a new installation - NOT attempt upgrade. – Milliways Jun 30 at 23:45
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    @milliways where's the fun in that? But my question is not about the merits of upgrading, but if the same disk used for a pi3 will work on a pi3, assuming it's running Buster. – askvictor Jul 1 at 0:41
  • make a backup and try - I went from jessie->stretch without issue on my pi, and that was a far bigger change than stretch->buster - except for the MUCH larger boot partition requirement of course - but even that can, with some magic, be handled – Jaromanda X Jul 1 at 9:28
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Upgrading to Buster from Stretch isn't recommended. Install a new card and copy your old programs & data from the old system.

As long as you get the new kernel and firmware/bootcode for the BCM2711 processor installed on your SDCard it will boot on a RPi4.

If the card has NOOBS then forget it. Updating NOOBS for a new processor is a pain (always has been). It's not impossible, but it's not easy.

  • FWIW I upgraded fine from Buster to Stretch on my Pi 3 (with a few hiccups). However, moving the SD card to a Pi 4 failed. What do you mean exactly by the second paragraph? How would we do that precisely? – Sparhawk Sep 21 at 13:00
  • I actually think my question is slightly different to this, because the Stretch -> Buster part isn't relevant. I've opened a new question. – Sparhawk Sep 22 at 0:42
  • You need to ensure that the stuff in the /boot folder in partition #1 (and partition #5 if NOOBS) has the kernel and bootcode for a RPi4. If you don't understand that then you have no choice but to build a fresh new SDCard for your new RPi4. – Dougie Sep 22 at 6:16
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This can be done, but requires a bit of work to get the bootloader updated for Raspberry Pi 4. Here's how I did it:

  1. Back up your SD card!!! This can go wrong any number of ways. Not my fault if you bork something!
  2. Upgrade Raspbian on your Pi 3 to Raspbian Buster.
  3. Use Gparted on another computer to enlarge the boot partition of the card to 250MB. Make sure you don't move the start position of the boot partition.
  4. Put the card back in the Pi 3 and update the bootloader with the command sudo apt install --reinstall raspberrypi-bootloader raspberrypi-kernel
  5. Put the card in your Pi 4 and hope for the best.
  • won't work. apt install --reinstall raspberrypi-kernel will auto-remove the /boot/kernel7l.img needed by Raspberry pi 4... – JB. Oct 26 at 21:00
  • It worked for me, once my boot partition was enlarged. – Tim Morgan Oct 27 at 15:42

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