500 error after nextcloud update

Nextcloud version (eg, 12.0.2): 17.0.3 -> 18.0.1
Operating system and version (eg, Ubuntu 17.04): ubuntu 18.04
Apache or nginx version (eg, Apache 2.4.25): apache2.4.29
PHP version (eg, 7.1): 7.4.3

The issue you are facing:
500 error at index

Is this the first time you’ve seen this error? (Y/N): y

Steps to replicate it:

  1. nextcloud is version 17.0.3
  2. update nextcloud to 18.0.1(use updater)
  3. Update Done! --> Redirect to index --> 500 Internal error

The output of your Nextcloud log in Admin > Logging:

cant access

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

$CONFIG = array (
  'instanceid' => '**BLIND**',
  'passwordsalt' => '**BLIND**',
  'secret' => '**BLIND**',
  'trusted_domains' =>
  array (
    0 => '**BLIND**',
    1 => '**BLIND**',
  ),
  'datadirectory' => '/cloud/home',
  'dbtype' => 'mysql',
  'version' => '17.0.3.1',
  'overwrite.cli.url' => '**BLIND**',
  'dbname' => '**BLIND**',
  'dbhost' => 'localhost:3306',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => '**BLIND**',
  'dbpassword' => '**BLIND**',
  'installed' => true,
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'smtp',
  'mail_from_address' => '**BLIND**',
  'mail_domain' => '**BLIND**',
  'maintenance' => false,
  'theme' => '',
  'loglevel' => 2,
  'updater.release.channel' => 'stable',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'has_rebuilt_cache' => true,
  'mail_smtpsecure' => 'ssl',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtpauth' => 1,
  'mail_smtphost' => '**BLIND**',
  'mail_smtpport' => '465',
  'mail_smtpname' => '**BLIND**',
  'mail_smtppassword' => '**BLIND**',
  'default_language' => 'ko',
  'default_locale' => 'ko_KR',
  'knowledgebaseenabled' => 'false',
  'htaccess.RewriteBase' => '/',
  'trashbin_retention_obligation' => 'auto, 7',
  'app_install_overwrite' =>
  array (
    0 => 'admin_notifications',
  ),
  'updater.secret' => '**BLIND**',
);

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

There is no log in error.log

Looks like the config is not updated??
But when you connect to http://url/status, it looks like this:
{"installed":true,"maintenance":false,"needsDbUpgrade":true,"version":"18.0.1.3","versionstring":"18.0.1","edition":"","productname":"**BLIND**","extendedSupport":false}

I tried to enter http://url/updater directly in the url, and I asked for the updater.secret. I copied and pasted what was in config.php but said Invalid password.

help me please!!

sudo -u www-data occ upgrade -vv
I solved it.