I was almost hit by first Murphy’s rule : Never try to fix something working !
I made a backup and export my NCP setting.
I wrote a new NCP image (1.52 + NC26 and PHP8).
I restored my backup and import my settings. (logically went back to NC25 but with PHP8.0)
=> the path to my datas was not restored, my Let’s encrypt was not working (couldn’t write registered adress file).
As I only have one MicroSD card I have to joggle between images.
At the end, I restored my NC25/PHP7.4 image and got my setup working again.
Think I’ll wait for Armbian update (this summe as other Debian distro) to have PHP8.0 properly installed and then update to NC26.