OTA downgrande from 6.3.0 to 4.2.0

Firmware
1

Hi,

I have some borons in the field that are running 6.3.0 today.
I'd like to troubleshooting something and for that I need to downgrade them over the air from 6.3.0 to 4.2.0.

I undestood from this tutorial that I could achieve that by flashing these parts:

Questions:

  • what is the right order?
  • should I flash all of them?
  • can I do this with the command:

particle cloud flash 102308109823908108923 firmware.bin

Thanks!

2

That really isn't recommended. If you try this, try it first on device on your desk that you can fix using USB because it could get into a state where it no longer boots.

Generally the order for downgrading is the opposite of upgrading, so user firmware (that targets an older version), system, then bootloader. Between those two versions, SoftDevice should be the same, so you shouldn't need to flash that.

The reason it's not recommended is that downgrading OTA is not tested, and there is always the possibility that, for example, when booting the old system with a new bootloader, which should work, it does not, then the device can only be fixed by USB, or sometimes only by SWD.

In some other combinations of versions, though not yours, you can sometimes need an intermediate downgrade. This happened when switching from 128K to 256K binaries, when the modem baud rates changed, when Electron went from 2 to 3 system parts and similar uncommon situations.

If the device is in a product, make sure you mark as development before attempting this. Also watch the cloud logs to see what it's doing, because if the steps aren't exactly right, the device will begin upgrading while you are in the process of downgrading.

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