Sorry for my poor english.
Here is my problem. I wanted to update my version of nextcloud on o2switch with the updater, I was starting from a fairly old version and the update was done correctly from version to version until 24, the switch to the 25 seemed to go all the way until the launch https://xxxx.a4.swdrive.fr/, at which point a blank page appears and nothing. In FTP in the Nextclouddata/updaterxxx/backups folder I spotted nextcloud backups but I don’t know how to restore them. I launched the o2switch JetBackup tool and restored the Nextcloud and Nextclouddata folders and the corresponding database to an earlier version. Without success. I’m guessing there’s a setting somewhere. Reading me you have understood that I am only an amateur even if I have some notions, so thank you in advance for your kindness with if possible answers adapted to my level, but I have seen such on this forum I am confident.