I get a write permissions error while updating through the gui
Check for write permissions
The following places can not be written to:
/var/www/nextcloud/updater/…/robots.txt
/var/www/nextcloud/updater/…/db_structure.xml
/var/www/nextcloud/updater/…/index.html
/var/www/nextcloud/updater/…/.htaccess
/var/www/nextcloud/updater/…/AUTHORS
/var/www/nextcloud/updater/…/.user.ini
/var/www/nextcloud/updater/…/remote.php
/var/www/nextcloud/updater/…/index.php
/var/www/nextcloud/updater/…/public.php
/var/www/nextcloud/updater/…/console.php
/var/www/nextcloud/updater/…/version.php
/var/www/nextcloud/updater/…/status.php
/var/www/nextcloud/updater/…/occ
/var/www/nextcloud/updater/…/cron.php