Error 500 - NC 20.0.7.1 - on page Settings and App Store

Nextcloud version (eg, 20.0.5): 20.0.7.1
Operating system and version (eg, Ubuntu 20.04): TrueNAS-12.0-U2
PHP version (eg, 7.4): 7.4.15

The issue you are facing:
When i want to access the settings, app store pages i get 500 internal error

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

The output of your Nextcloud log in Admin > Logging:

{“reqId”:“EWtbvARYMZHq8IHgPvBh”,“level”:3,“time”:“2021-02-19T00:26:28+00:00”,“remoteAddr”:“192.168.2.221”,“user”:“ncadmin”,“app”:“PHP”,“method”:“GET”,“url”:"/settings/apps",“message”:“Class OCA\Support\Subscription\SubscriptionAdapter contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (OCP\Support\Subscription\ISubscription::isHardUserLimitReached) at /usr/local/www/nextcloud/apps/support/lib/Subscription/SubscriptionAdapter.php#30”,“userAgent”:“Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.152 Safari/537.36”,“version”:“20.0.7.1”}

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

<?php
$CONFIG = array (
  'apps_paths' =>
  array (
    0 =>
    array (
      'path' => '/usr/local/www/nextcloud/apps',
      'url' => '/apps',
      'writable' => true,
    ),
    1 =>
    array (
      'path' => '/usr/local/www/nextcloud/apps-pkg',
      'url' => '/apps-pkg',
      'writable' => true,
    ),
  ),
  'logfile' => '/var/log/nextcloud/nextcloud.log',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'passwordsalt' => '**********************************************',
  'secret' => '*****************************************************',
  'trusted_domains' =>
  array (
    0 => 'localhost',
    1 => '192.168.2.6',
  ),
  'datadirectory' => '/usr/local/www/nextcloud/data',
  'dbtype' => 'mysql',
  'version' => '20.0.7.1',
  'overwrite.cli.url' => 'http://localhost',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'oc_ncadmin',
  'dbpassword' => '6jwhblUipwdF9+h1uBMojW9YOsBe0F',
  'installed' => true,
  'instanceid' => 'ocpahwsp846i',
  '

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

2021/02/19 01:26:39 [error] 18502#102058: *174 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Class OCA\Support\Subscription\SubscriptionAdapter contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (OCP\Support\Subscription\ISubscription::isHardUserLimitReached) in /usr/local/www/nextcloud/apps/support/lib/Subscription/SubscriptionAdapter.php on line 30" while reading response header from upstream, client: 192.168.2.221, server: _, request: "GET /settings/user HTTP/1.1", upstream: "fastcgi://unix:/var/run/nextcloud-php-fpm.sock:", host: "192.168.2.6:8282"

Just our of curiosity, have you looked at your oc_file_locks in your DB? is it high?

I was getting an error like this. It ended up being an app. Perhaps a News app or do you have any external facing apps? If you have high file locks in your DB, then look for File locked fixes.

Something like this: File is locked - how to unlock

Keep in mind that I am not sure if your issue and mine are/were the same. I was also getting some News app errors, but there was an update today, that hopefully will fix those.

Thanks for your reply @DuffyCloud.
I try your solution but didn’t work. I stil have the same issue

I found the solution.
The issue is with the app support !

make those two command in the console
cd /usr/local/www/nextcloud/apps
rm -fR support

Everithing is working just fine now.