I lately moved my Archer C7 v2 running OpenWRT from 18.06 using the ar71xx target to 19.07rc2 using the new ath79 target. Since the release notes are a bit sparse regarding how to achieve the target move, I asked on the IRC channel. Basically you can use sysupgrade as usual, but you have to

• use force -F and
• drop the config -n

That implies you have to manually backup your config (basically /etc). I decided to drop everything, since I wanted to repurpose the device slightly.

As a first step I did a reset:

firstboot && reboot now

After setting the password again I scp'ed the ath79 sysupgrade image for the device, and installed it with

sysupgrade -F -n /tmp/tplink_archer-c7-v2-squashfs-sysupgrade.bin

After several minutes the "sun" LED on the right to the power led was just blinking, but the device was still unresponsive so I did a full power cycle, and a minute later it was back on.

Thanks to PaulFertser from #openwrt on Freenode.

Upgrade sidenote for dnsmasq and DNSSEC

Usually I install dnsmasq-full to have DNSSEC support. So every time I upgrade I've to remember to disable dnssec before upgrading, because after the upgrade only the default dnsmasq is available, which will fail to start due to a config option it can not understand.