/!\ Possible duplicate of Mise à jour manuelle d'application / gestion de versions .
But
sudo -u nextcloud php /var/www/nextcloud/occ app:disable user_external
says that there is no such app ( user_external ) installed.
Thans to @nimch, I was able to update to version 14.0.4 using this command :
sudo yunohost app upgrade nextcloud -u https://github.com/YunoHost-Apps/nextcloud_ynh/tree/e289fb47b23d9ac626ee5ae85b6d79a2c898b8ab
But this error was raised several times, and again when I tried to reload nginx :
sh: 0: getcwd() failed: No such file or directory
Ok it seems it only needed a reboot. Now, Nextcloud main page leads to a beautiful :
Internal Server Error
Trying to get to the version 15 through regular update failed.
Log is available here : https://paste.yunohost.org/raw/latocusepa but I don’t have time to have a look for now.