on a EdgeOS v2 firmware ER X-SFP, I get a "Cannot find upgrade image" failure message:
admin@gw:/tmp$ cat /etc/version
EdgeRouter.ER-e50.v2.0.9-hotfix.2.5402463.210511.1317
admin@gw:~$ add system image /tmp/openwrt-18.06-snapshot-r7911-f65330d27d-ramips-mt7621-ubnt-erx-initramfs-factory.tar
Version [v2.0.9-hotfix.1.5371034.210122.1014] is about to be replaced
Are you sure you want to replace old version? (Yes/No) [Yes]:
Cannot find upgrade image. Upgrade failed.
admin@gw:~$ add system image /tmp/openwrt-19.07.7-ramips-mt7621-ubnt-erx-sfp-initramfs-kernel.bin
Version [v2.0.9-hotfix.1.5371034.210122.1014] is about to be replaced
Are you sure you want to replace old version? (Yes/No) [Yes]: yes
Checking upgrade image...Upgrade image does not support the device. Upgrade failed.
I presume this is something that has changed in Ubiqiuti's v2 firmware; I will try next to switch to EdgeOS v1 and try the openwrt install as above from there. Any other ideas?
As I understand the stman repo readme, the root problem is that the factory image is missing as the openwrt build fails as a result of a slightly-too-large kernel image. stman trimmed the kernel build and graciously provides a working factory tar file from which you can then sysupgrade to a stock openwrt image per the ToH directions. I had to force the sysupgrade as the stman image is for an ubnt-erx and not ubnt-erx-sfp, I switched to latter for the final install as that is the hardware I have.
I will try and update the wiki with this info a little later.