No cache entry found

Nextcloud version: 15.0.0
Operating system and version: Ubuntu 18.04 LTS
Apache: 2.4.29
PHP version: 7.3

The issue you are facing:
I converted owncloud to nextcloud. Everything ist running. But I see error-messages in the logfile.

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

The output of your Nextcloud log in Admin > Logging:
I see much entrys like this in my log-file:

No cache entry found for /appdata_50f2b69bdd312/avatar/user/avatar.jpg (storage: local::/var/www/nextcloud/data/, internalPath: appdata_50f2b69bdd312/avatar/gerhard/avatar.jpg)
....

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

<?php
$CONFIG = array (
  'instanceid' => '50f2b69sdfsdfbdd312',
  'passwordsalt' => '78c33d331f4ddbsfsdfcb763a26dd5263a3',
  'datadirectory' => '/var/www/nextcloud/data',
  'dbtype' => 'mysql',
  'version' => '15.0.0.10',
  'installed' => true,
  'maintenance' => false,
  'theme' => '',
  'trusted_domains' =>
  array (
    0 => 'localhost',
    1 => '192.168.2.201',
    2 => 'mycloud.dynvpnserver.de',
  ),
  'trusted_proxies' =>
  array (
    1 => 'myreverseproxy',
    2 => 'mycloud.dynvpnserver.de',
  ),
  'loglevel' => 0,
  'mail_from_address' => 'sysadministrator',
  'mail_smtpmode' => 'smtp',
  'mail_domain' => 'smtp.mailserver',
  'mail_smtphost' => 'smtp.mailserver',
  'mail_smtpport' => '25',
  'secret' => '94112ef32c6fd2ab1c9fc0037114678sdfsdfa12e81c3e28628b0e553a34955492a12sdfeb3110d87cf3838499afcd4f70
f46fsdfaf9e',
  'dbname' => 'nextcloudy',
  'dbhost' => '192.168.1.202',
  'dbuser' => 'nextcloudy',
  'dbpassword' => 'secret$$',
  'updatechecker' => false,
  'overwrite.cli.url' => 'http:/myserver/owncloud',
  'logtimezone' => 'Europe/Berlin',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'memcache.locking' => '\\OC\\Memcache\\Redis',
  'redis' =>
  array (
    'host' => 'localhost',
    'port' => 6379,
  ),
  'memcache.distributed' => '\\OC\\Memcache\\Memcached',
  'memcached_servers' =>
  array (
    0 =>
    array (
      0 => 'localhost',
      1 => 11211,
    ),
  ),
  'default_language' => 'de',
);

The output of your Apachesystem log in `/var/log/apache.err:

[Tue Apr 02 06:53:02.694215 2019] [mpm_prefork:notice] [pid 1912] AH00163: Apache/2.4.29 (Ubuntu) configured -- resuming normal operations
[Tue Apr 02 06:53:02.694242 2019] [core:notice] [pid 1912] AH00094: Command line: '/usr/sbin/apache2'
[Tue Apr 02 14:37:29.242359 2019] [authz_core:error] [pid 7012] [client 192.168.3.254:55323] AH01630: client denied by server configuration: /var/www/nextcloud/data/.ocdata
[Tue Apr 02 14:37:34.697019 2019] [authz_core:error] [pid 12458] [client 192.168.3.254:55335] AH01630: client denied by server configuration: /var/www/nextcloud/data/.ocdata
[Tue Apr 02 14:37:45.187629 2019] [authz_core:error] [pid 7009] [client 192.168.3.254:55367] AH01630: client denied by server configuration: /var/www/nextcloud/data/.ocdata

Same issue, can’t use my cloud anymore.
Could you grab a clue on this error?

I don´t have any solution for this error.