Windows client keeps crashing

I have an annoying problem with my Windows client.
It keeps crashing randomly when checking for changes. Sometimes it dies after a few minutes and sometimes it runs for a few hours. But now it seems i have so much folders/files that it never reaches the actual upload part. If i leave it over night it has crashed and not uploaded anything.
So right now it does not work at all.
The server seems to be working fine no problems at all. And the smaler synced folders are working ok. But not the larger folder i have.

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Nextcloud version : 16.0.4
Operating system and version : Ubuntu 17.04
Apache or nginx version: Apache/2.4.38 (Ubuntu)
PHP version: 7.3.3

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

Steps to replicate it:

  1. Start the client and wait for it to crash

The output of your Nextcloud log in Admin > Logging:

Debug	no app in context	SCSSCacher: css cache cleared!		2019-08-20T23:04:53+0200
Debug	core	starting upgrade from 16.0.3.0 to 16.0.4.1		2019-08-20T23:04:51+0200
Error	jsresourceloader	Could not find resource js/config.js to load		2019-08-20T23:04:50+0200
Fatal	webdav	Sabre\DAV\Exception\BadRequest: expected filesize 100000000 got 25231360		2019-08-14T16:57:51+0200
Error	no app in context	Sabre\DAV\Exception\BadRequest: expected filesize 100000000 got 25231360		2019-08-14T16:57:51+0200
Fatal	webdav	Sabre\DAV\Exception\BadRequest: expected filesize 100000000 got 7602176		2019-08-14T16:57:40+0200
Error	no app in context	Sabre\DAV\Exception\BadRequest: expected filesize 100000000 got 7602176		2019-08-14T16:57:40+0200
Error	PHP	unlink(/media/nextcloud/appdata_oc7o093b2m8q/css/core/b583-687c-server.css): No such file or directory at /var/www/html/nextcloud/lib/private/Files/Storage/Local.php#228		2019-08-12T21:05:53+0200
Debug	core	starting upgrade from 16.0.0.9 to 16.0.3.0		2019-08-

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

<?php
$CONFIG = array (
  'instanceid' => 'x',
  'passwordsalt' => 'x+TAVvgSbgl+x',
  'secret' => 'x+si2i644cXCgrCBEph/x',
  'trusted_domains' =>
  array (
    0 => 'x.x.com',
  ),
  'datadirectory' => '/media/nextcloud',
  'dbtype' => 'mysql',
  'version' => '16.0.4.1',
  'overwrite.cli.url' => 'https://x.x.com',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'xx',
  'dbpassword' => 'x',
  'installed' => true,
  'activity_expire_days' => 14,
  'auth.bruteforce.protection.enabled' => 'false',
  'blacklisted_files' =>
  array (
    0 => '.htaccess',
    1 => 'Thumbs.db',
    2 => 'thumbs.db',
  ),
  'cron_log' => true,
  'enable_previews' => true,
  'enabledPreviewProviders' =>
  array (
    0 => 'OC\\Preview\\PNG',
    1 => 'OC\\Preview\\JPEG',
    2 => 'OC\\Preview\\GIF',
    3 => 'OC\\Preview\\BMP',
    4 => 'OC\\Preview\\XBitmap',
    5 => 'OC\\Preview\\Movie',
    6 => 'OC\\Preview\\PDF',
    7 => 'OC\\Preview\\MP3',
    8 => 'OC\\Preview\\TXT',
    9 => 'OC\\Preview\\MarkDown',
  ),
  'filesystem_check_changes' => 0,
  'filelocking.enabled' => 'true',
  'htaccess.RewriteBase' => '/',
  'integrity.check.disabled' => false,
  'knowledgebaseenabled' => false,
  'logfile' => '/var/nc_data/nextcloud.log',
  'loglevel' => 2,
  'logtimezone' => 'Europe/Berlin',
  'log_rotate_size' => 104857600,
  'maintenance' => false,
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'memcache.locking' => '\\OC\\Memcache\\Redis',
  'overwriteprotocol' => 'https',
  'preview_max_x' => 1024,
  'preview_max_y' => 768,
  'preview_max_scale_factor' => 1,
  'redis' =>
  array (
    'host' => '/var/run/redis/redis-server.sock',
    'port' => 0,
    'timeout' => 0.0,
  ),
  'quota_include_external_storage' => false,
  'share_folder' => '/Shares',
  'skeletondirectory' => '',
  'theme' => '',
  'trashbin_retention_obligation' => 'auto, 7',
  'updater.release.channel' => 'stable',
  'updater.secret' => 'xxx',
);

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

[Tue Aug 20 00:06:56.386418 2019] [mpm_event:notice] [pid 911:tid 140100967922624] AH00489: Apache/2.4.38 (Ubuntu) OpenSSL/1.1.1b configured -- resuming normal operations
[Tue Aug 20 00:06:56.386432 2019] [core:notice] [pid 911:tid 140100967922624] AH00094: Command line: '/usr/sbin/apache2'
[Tue Aug 20 10:16:22.787229 2019] [authz_core:error] [pid 31432:tid 140100314801920] [client 90.226.53.155:57364] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
[Tue Aug 20 10:52:00.652123 2019] [proxy_fcgi:error] [pid 31431:tid 140100331587328] (20014)Internal error (specific information not available): [client 176.58.124.134:55332] AH01075: Error dispatching request to : (reading input brigade)
[Tue Aug 20 14:33:51.922753 2019] [authz_core:error] [pid 12399:tid 140100528420608] [client 90.226.53.155:58234] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
[Tue Aug 20 14:35:12.041866 2019] [authz_core:error] [pid 12399:tid 140099853465344] [client 90.226.53.155:58285] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
[Tue Aug 20 14:36:37.510124 2019] [authz_core:error] [pid 12399:tid 140100012861184] [client 90.226.53.155:58317] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
[Tue Aug 20 17:52:21.548611 2019] [authz_core:error] [pid 23650:tid 140099048158976] [client 90.226.53.155:53212] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
[Tue Aug 20 17:56:37.599796 2019] [authz_core:error] [pid 25703:tid 140100423907072] [client 90.226.53.155:53429] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
[Tue Aug 20 23:04:24.366017 2019] [autoindex:error] [pid 25703:tid 140100830803712] [client 90.226.53.155:58947] AH01276: Cannot serve directory /var/www/html/nextcloud/settings/: No matching DirectoryIndex (index.php,index.html) found, and server-generated directory index forbidden by Options directive
[Tue Aug 20 23:05:22.839305 2019] [authz_core:error] [pid 25703:tid 140100113508096] [client 90.226.53.155:58989] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
[Tue Aug 20 23:05:39.121643 2019] [authz_core:error] [pid 29746:tid 140100272903936] [client 90.226.53.155:59007] AH01630: client denied by server configuration: /var/www/html/nextcloud/config
error.log (END)

Hi ,
since update from 16.0.3 to 16.0.4 I have a similar problem. Seems to be a problem of the windows sync client (2.5.3) with this version.
Nextcloud is running on a debian linux on readynas arm 6 with apache2, mysql and php 7.2.