No app debug messages in nextcloud.log

Nextcloud version 13.0.1:
Operating system and version CentOS 7.4:
Apache or nginx version Nginx 1.12.2:
PHP version 7.2.4:

The issue you are facing:

After enabling debug level 0 , I see only cron debug messages. There are none of enablined application messages

Is this the first time you’ve seen this error? N):

Steps to replicate it:

  1. Add ‘loglevel’ => 0 in config.php
  2. restart nginx
  3. restart php-fpm

The output of your Nextcloud log in Admin > Logging:

|Debug|cron|Finished OCA\Activity\BackgroundJob\EmailNotification job with ID 7 in 0 seconds|2018-04-13T09:59:46-0400|
|---|---|---|---|
|Debug|cron|Run OCA\Activity\BackgroundJob\EmailNotification job with ID 7|2018-04-13T09:59:46-0400|
|Debug|cron|Finished OCA\Spreed\BackgroundJob\ExpireSignalingMessage job with ID 18 in 0 seconds|2018-04-13T09:59:46-0400|
|Debug|cron|Run OCA\Spreed\BackgroundJob\ExpireSignalingMessage job with ID 18|2018-04-13T09:59:46-0400|
|Debug|cron|Finished OCA\Files\BackgroundJob\ScanFiles job with ID 9 in 0 seconds|2018-04-13T09:59:46-0400|

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

<?php
$CONFIG = array (
  'instanceid' => 'instance id here',
  'passwordsalt' => 'salt here',
  'secret' => 'secret here',
  'trusted_domains' => 
  array (
    0 => 'vclouda.leshik.online',
  ),
  'datadirectory' => '/usr/share/nginx/html/nextcloud/data',
  'overwrite.cli.url' => 'https://vclouda.leshik.online/nextcloud',
  'loglevel' => 0,
  'debug' => true,
  'dbtype' => 'pgsql',
  'version' => '13.0.1.1',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'nc_user',
  'dbpassword' => 'password here',
  'installed' => true,
  'maintenance' => false,
  'mail_from_address' => 'no-reply',
  'mail_smtpmode' => 'php',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_domain' => 'leshik.online',
  'mail_smtpsecure' => 'tls',
  'mail_smtpauth' => 1,
  'mail_smtphost' => 'smtp.gmail.com',
  'mail_smtpport' => '587',
);

The output of your Apache/nginx/system log in /var/log/____:

# cat /var/log/nginx/error.log

2018/04/13 13:16:41 [error] 1097#0: *4630 access forbidden by rule, client: 173.49.202.209, server: vclouda.leshik.online, request: "GET /nextcloud/data/.ocdata?t=1523625401655 HTTP/2.0", host: "vclouda.leshik.online"
2018/04/13 13:16:46 [error] 1097#0: *4630 access forbidden by rule, client: 173.49.202.209, server: vclouda.leshik.online, request: "GET /nextcloud/data/.ocdata?t=1523625406075 HTTP/2.0", host: "vclouda.leshik.online"
2018/04/13 13:38:09 [error] 1097#0: *4865 access forbidden by rule, client: 173.49.202.209, server: vclouda.leshik.online, request: "GET /nextcloud/data/.ocdata?t=1523626689569 HTTP/2.0", host: "vclouda.leshik.online"