[SOLVED] Yunohost injoignable après màj échouée de Nextcloud

It worked !
but…
Nextcloud returns a 502 Bad Gateway error…
I restarted nginx, rebooted and diagnosis is ok…

So I looked for a solution and Yunohost GUI invited me to update Nextcloud.
I tried again and same problem…

EDIT ------------
Here the log for Nextcloud update :

2018-12-16 18:06:51,846: WARNING - Data dir will not be saved, because backup_core_only is set.
2018-12-16 18:12:46,669: WARNING - 
2018-12-16 18:12:46,693: WARNING - Upgrade to nextcloud 13.0.0
2018-12-16 18:16:23,480: WARNING - Unable to upgrade Nextcloud
2018-12-16 18:16:23,572: WARNING - !!
2018-12-16 18:16:23,574: WARNING -   nextcloud's script has encountered an error. Its execution was cancelled.
2018-12-16 18:16:23,576: WARNING - !!
2018-12-16 18:16:23,577: WARNING - Upgrade failed.
2018-12-16 18:17:21,859: WARNING - Removing database nextcloud
2018-12-16 18:17:49,209: WARNING - Remove the user nextcloud
2018-12-16 18:24:13,707: WARNING - debconf: unable to initialize frontend: Dialog
2018-12-16 18:24:14,001: WARNING - debconf: (Dialog frontend will not work on a dumb terminal, an emacs shell buffer, or without a controlling terminal.)
2018-12-16 18:24:14,003: WARNING - debconf: falling back to frontend: Readline
2018-12-16 18:24:14,004: WARNING - debconf: unable to initialize frontend: Readline
2018-12-16 18:24:14,006: WARNING - debconf: (This frontend requires a controlling tty.)
2018-12-16 18:24:14,008: WARNING - debconf: falling back to frontend: Teletype
2018-12-16 18:24:14,009: WARNING - dpkg-preconfigure: unable to re-open stdin:
2018-12-16 18:25:44,413: WARNING - The app was restored to the way it was before the failed upgrade.
2018-12-16 18:25:44,540: ERROR - Impossible de mettre à jour nextcloud

END EDIT------------

I start again and now I have an old not working Nextcloud installation… In order to update I follow your post but no /temp in my fstab configuration :

proc            /proc           proc    defaults          0       0
/dev/mmcblk0p1  /boot           vfat    defaults          0       2
/dev/sda1       /               ext4    defaults,noatime  0       1
# a swapfile is not a swap partition, no line here
#   use  dphys-swapfile swap[on|off]  for that

What can I do for a proper update ?
Thank you so much for your help !