Nextcloud client large file sync fails with "connexion closed"

Nextcloud version : 14.0.4
Operating system and version : Debian 9
Apache or nginx version : 2.4.25-3+deb9u6
PHP version : 7.2

The issue you are facing:

Can’t upload large file (650 mb±), client displays error " connexion closed".

Screenshot%20from%202018-11-24%2013-28-28

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

Steps to replicate it:

  1. Copy folder wich contains large file(s)
  2. Wait for client start upload
  3. Client progression go sometime backwards
  4. Client stops sync : " connexion closed"

.htaccess

php_value upload_max_filesize 511M
php_value post_max_size 511M
php_value memory_limit 512M

apache.conf

Timeout 300
KeepAlive On
KeepAliveTimeout 500

On php.ini max upload is 16G…

The output of your Nextcloud log in Admin > Logging:

https://pastebin.com/C53BHphA

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

<?php
$CONFIG = array (
  'instanceid' => 'oc1j22tq1wal',
  'passwordsalt' => '<removed>',
  'secret' => '<removed>',
  'trusted_domains' => 
  array (
    0 => '<redacted domain>',
  ),
  'datadirectory' => '/mnt/md127/nextcloud/data',
  'overwrite.cli.url' => 'https://<redacted domain>/',
  'dbtype' => 'mysql',
  'version' => '14.0.4.2',
  'dbname' => 'nextcloud_db',
  'dbhost' => 'localhost',
  'dbtableprefix' => 'oc_',
  'dbuser' => '<removed>',
  'dbpassword' => '<removed>',
  'logtimezone' => 'UTC',
  'installed' => true,
  'mail_smtpmode' => 'sendmail',
  'mail_from_address' => 'admin',
  'mail_domain' => '<removed>',
  'loglevel' => 0,
  'mail_smtphost' => '<removed>',
  'maintenance' => false,
  'appstore.experimental.enabled' => true,
  'theme' => '',
  'updatechecker' => false,
  'htaccess.RewriteBase' => '/',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'updater.release.channel' => 'stable',
  'data-fingerprint' => '1780097d5b25888d3ac0b8c81046473a',
  'mail_smtpport' => '587',
  'mail_smtpsecure' => 'tls',
  'updater.secret' => '$2y$10$qj0W6p0V.SAKFEWrarrJPeNWMW..91LMkQblO5WZtwvm2k8h3W5Wi',
);

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

https://pastebin.com/r0Z5MFar

Previous uploads of 4G+ worked with no problems before.

Same file, same server but different client (old 2.3.3) and the file gets uploaded like a charm.

Latest client is the culprit.