Probleme UpDate 15.0.6


I have a Nextcloud 15.0.4 on my dedicated server (Debian 8.11, Php 7.1 ,Mysql 5.5.62 ), I want to update it to version 15.0.6 as proposed in the graphical interface of my Nextcloud. But when I click on the link, to download the new version but I get a page that says:

  • Initializing

Current version is 15.0.4.
Update to Nextcloud 15.0.6 available. (channel: “stable”)
Following file will be downloaded automatically:

  • Check for expected files

  • Check for write permissions

  • Create backup

  • Downloading

  • Verifying integrity

  • Extracting

  • Enable maintenance mode

  • Replace entry points

  • Delete old files

  • Move new files in place

  • Keep maintenance mode active?

  • Done

Go back to your Nextcloud instance to finish the update

I click on this link and I come back to my interface, the version number is still 15.0.4 and I do not see the update step that I knew until version 15.0.4.

What should I do to update in 15.0.6?

Please Thank you