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Sorry to hear you’re facing problems 
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In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 12.0.2): 16.0.0.9
Operating system and version (eg, Ubuntu 17.04): Debian GNU/Linux 9
Apache or nginx version (eg, Apache 2.4.25):
PHP version (eg, 7.1): 7.2.18
The issue you are facing:
Getting error
Internal Server Error
The server encountered an internal error and was unable to complete your request.
Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.
More details can be found in the server log.
When I checked logs I see below message in log.
message":{“Exception”:“OC\HintException”,“Message”:“Memcache \OC\Memcache\Redis not available for local cache”,“Code”:0,“Trace”:[{“file”:“/var/www/nextcloud/lib/private/Server.php”,“line”:510,“function”:“__construct”,“class”:"OC\Memcache\Factory
Is this the first time you’ve seen this error? (Y/N): Y
Config file:
<?php
$CONFIG = array (
....some lines missin....
'dbtype' => 'mysql',
'version' => '16.0.0.9',
'overwrite.cli.url' => 'https://myprivatecloud.ddns.net/',
'dbname' => 'nextcloud',
'dbhost' => 'localhost',
'dbport' => '',
'dbtableprefix' => 'oc_',
'mysql.utf8mb4' => true,
'dbuser' => 'user',
'dbpassword' => '******',
'installed' => true,
'instanceid' => 'ocjpzbw8dip4',
'memcache.local' => '\\OC\\Memcache\\Redis',
'memcache.locking' => '\\OC\\Memcache\\Redis',
'redis' =>
array (
'host' => '/var/run/redis/redis.sock',
'port' => 0,
'timeout' => 0.0,
'password' => '*****',
),
'tempdirectory' => '/media/myCloudDrive/nc-data/tmp',
'mail_smtpmode' => 'smtp',
'mail_smtpauthtype' => 'LOGIN',
'mail_from_address' => 'admin',
'mail_domain' => 'ownyourbits.com',
'jpeg_quality' => '60',
'overwriteprotocol' => 'https',
'maintenance' => false,
'logfile' => '/media/myCloudDrive/nc-data/nextcloud.log',
'loglevel' => 2,
'app_install_overwrite' =>
array (
0 => 'admin_notifications',
),
'mail_sendmailmode' => 'smtp',
'mail_smtpsecure' => 'ssl',
);