1.14 on AC1200

[softstorm]

Back in 2022 I flashed gargoyle_1.13.0-ramips-mt7621-r6220-squashfs-factory.bin onto my two Netgear AC1200s, working great. Recently I went to upgrade one using gargoyle_1.14.0-ramips-mt7621-netgear_r6220-squashfs-sysupgrade.bin, but no joy. I get the error message "Firmware has been detected as incompatible with this device (wrong device OR too big OR invalid firmware format)". Where did I go wrong?

[pythonic]

I have an R6220 in service at the moment with a personal build of 1.14 without problems. Did you try and keep the configuration? I ask because the MT7621 sub-target had a major change to how the ethernet switch is managed at 1.14 (known in OpenWrt as the transition from "swconfig" to "DSA") and you can't keep your configuration with this upgrade (well you can try but expect to soft-brick the device...).

[softstorm]

No, I stopped when I got the warning and I didn't click Preserve Settings. I read that Netgear sets the partition we need at 18MB, not very big. But that's interesting you had success.

[softstorm]

Here is what I see, and the first two lines are trying to tell me something, as if it thinks I don't have an R6220. Are there different versions of that hardware?

Valid firmware:No
Firmware matches device:No
Supported devices:netgear,r6220
r6220
Firmware/Device Compatibile:No. Config cannot be migrated from swconfig to DSA
Firmware fits in flash memory:Yes
Checksum matches:-
MD5:72d8ecb89989fbd8e63a512583d15e4b
SHA-1:63a0ec7059789582a3c8fddd44cee2fa7911a0ec
SHA-256:aac3db6425788a1b3174b025f904da5f320560d174d4181ee5543a9315c6e0a1
Attempt to Preserve Settings: [ ]
Firmware has been detected as incompatible with this device (wrong device OR too big OR invalid firmware format). Forcing firmware upgrade can result in a bricked device if used incorrectly. Please ensure this firmware is correct for your device!
If you wish to force the upgrade, please tick Force upgrade below.

Force upgrade: [ ]

[Lantis]

You missed the most important line which is what pythonic referred to.

Firmware/Device Compatibile:No. Config cannot be migrated from swconfig to DSA

The upgrade should run fine if you don’t preserve settings and force it.

[pythonic]

I've just been able to flash that image to my R6220 without drama, including preserving my config, so the image appears to be fine.

It has been a while since I upgraded this unit to 1.14 so I don't recall exactly how it played out but I was definitely aware of the DSA transition and expecting the upgrade to complain at the time. The DSA and Upgrading sections of the OpenWrt 21.02.0 release notes may be helpful to review, as this release was the first with DSA converted targets.

I think, based on having run 1.14 (both official and my own builds) and perusal of the OpenWrt 21.02.0 release notes, that you should be able to upgrade but you will need to select the "force" option and not attempt to preserve the configuration to be successful.