I have MT7623N device and want to upgrade rather old lede (kernel 4.9.44) with newest OpenWrt 18.06 (kernel 4.14.91).
I cloned the repo, compiled it and got *-squashfs-sysupgrade.bin, but whenever I try to use it with sysupgrade I get
Image not in /tmp, copying... Image metadata not found The upgarde image is corrupt. Image check 'platform_check_image' failed.
The same happens with image downloaded from openwrt repository.
Is it possible to upgrade from LEDE to OpenWRT? I've noticed that for lede sysupgrade is a tar archive and here it is bin.