In the event of an issue the Nextcloud logs could help figure out a probable cause. Most activities and actions in Nextcloud are logged. An automated log rotation mechanism within Nextcloud clears and retains the logs regularly to prevent an overflow.

sudo lnav /var/snap/nextcloud/current/logs/nextcloud.log

sudo nextcloud.occ log:watch

sudo truncate -s 0 /var/snap/nextcloud/current/logs/nextcloud.log

• Logs for Nextcloud: /var/snap/nextcloud/current/logs/nextcloud.log
  • Note that this won't be the case if you've configured a custom data directory, for example somewhere in /media. The nextcloud logs will then be stored on that same directory.
• Logs for Apache2: /var/snap/nextcloud/current/logs/apache_access.log
• Logs for Redis: /var/snap/nextcloud/current/logs/redis.log
• Logs for PHP-FPM: /var/snap/nextcloud/current/logs/php-fpm_errors.log
• Logs for PHP: /var/snap/nextcloud/current/logs/php_errors.log
• Logs for Certbot: /var/snap/nextcloud/current/certs/certbot/logs/letsencrypt.log
• Logs for MySQL: /var/snap/nextcloud/current/logs/mysql_errors.log

@Kyrofa's blog

Nextcloud snap has several services contained within it. There are four that are most important for upgrade purposes:

• MySQL (nextcloud.mysql)
• PHP (nextcloud.php-fpm)
• Apache (nextcloud.apache)
• Nextcloud Fixer (nextcloud.nextcloud-fixer)

sudo snap logs -f nextcloud.mysql

sudo snap logs -f nextcloud.php-fpm

sudo snap logs -f nextcloud.apache

sudo snap logs -f nextcloud.nextcloud-fixer

Debugging script