U-boot merge for archer c20 v5 must be done only at first installation of OpenWrt?

Hello

I could build with
openwrt-21.02.3-ramips-mt76x8-tplink_archer-c20-v5-squashfs-sysupgrade.bin and and original boot loader an image to upload to C20 V5 which works.
Now I have compiled the source of 21.0.2.3 and build successfully an image and built the same way an image to upload with the original boot loader.
If I go to the upgrade process in OpenWRT it says me that the image is not compatible
Opening the original compiled sysupgrade image without putting boot loader in front the OpenWRT does not complain...

So my question. Do I have to mere the original u-boot only the first time to upload OpenWRT???
I don't want to mess up my router..

Thanks for hints

A sysupgrade image is meant to work as-is, ie no further modifications needed to have the OpenWrt sysupgrade mechanism parse it.

Can you share the specific error?

The warning if I merge image with uboot (like first installation).
In fact original installed image has the same warning

Here upload of sysupgrade C20 V5 image merged with u- boot like described below

Ok it tells to create the factory image this way, but I always have installed on all other devices the factory image never the sysupgrade to install new version of OpenWRT...

Archver C20 v5 Wifi

Here upload of plain sysupgrad C20 V5 image:
Sysupgrade1

So again will it be the right way to upgrade with "normal" sysupgrade image and new devices
first install only with the merg?

Do you get an error with the plain sysupgrade image, ie without u-boot integrated? That's what sysupgrade is for.

Please understand sysupgrade is an internal OpenWrt mechanism. The fact you prep a sysupgrade image by merging it with an extracted u-boot actually turns it into what OpenWrt would call a 'factory' image: an image you can install OpenWrt with coming from the OEM software or using the OEM provided recovery mechanisms (as you were doing to install OpenWrt).

If your OpenWrt supports sysupgrade - and it does, otherwise it would not offer you the command - then that's what you should use to upgrade with a plain sysupgrade image to a newer OpenWrt release.

Ok I will try it now. I have not done because I was in doubt...
Thanks a lot!