Unable to update to 15.0.5

Hi,

first of all many thanks for making Nextcloud available. It really is a fantastically useful tool! Unfortunately I am unable to update from 15.0.4 to 15.0.5.

I’ve tried the updater from within Nextcloud itself as well as php updater.phar and both yield the same result in that they claim to execute the update more or less immediately but don’t actually do anything.

Nextcloud version: 15.0.4
Operating system and version: Debian stable
Apache or nginx version: Apache2 Version 2.4.25
PHP version: 7.0.33

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

The output of your Nextcloud log in Admin > Logging:

	InvalidArgumentException: Invalid serialized command

    /var/www/nextcloud/lib/private/BackgroundJob/Job.php - line 61:

    OC\Command\CommandJob->run("O:33:\"OCA\ ... }")

    /var/www/nextcloud/lib/private/BackgroundJob/QueuedJob.php - line 44:

    OC\BackgroundJob\Job->execute(OC\BackgroundJob\JobList {}, OC\Log {})

    /var/www/nextcloud/cron.php - line 146:

    OC\BackgroundJob\QueuedJob->execute(OC\BackgroundJob\JobList {}, OC\Log {})

Here the update.log:

2019-03-09T15:07:12+0000 iVUADAYyor [info] checkForUpdate() Array
(
    [version] => 15.0.5.3
    [versionstring] => Nextcloud 15.0.5
    [url] => https://download.nextcloud.com/server/releases/nextcloud-15.0.5.zip
    [web] => https://docs.nextcloud.com/server/15/admin_manual/maintenance/upgrade.html
    [changes] => https://updates.nextcloud.com/changelog_server/?version=15.0.5
    [autoupdater] => 1
    [eol] => 0
    [signature] => agNeQvwNXkDCorrAQLBKn7s82D7HLCm0Q52hpp8dmrYQALZsSekiMXkMc/vN8H98
AzCoT3U2IeTDChMgc5oxV1I9JrD7o+zaqb2DNCBVEQ98ecqRlj6hs0+Kqxd9Zv3e
1p4NOc0VB//edxXr5vkIhnovja/gF+Z7cr6h2Jrshcgx6FZ1JNZfn51VHOrXPB5v
eD7LLOJWcP5nZ+HWDmrRrK16rcy86a+bcLY0Al2jdgzVKQJCVvvGloRa7GG5e/3P
HtmYIIKyDRMQb473PRDApXfVXUNqGrZ2XiDXlz2VmESmOEs3eiecNlVacZVkL7fW
jKugmbHOVnqP+CSJk4ID7Q==
)

2019-03-09T15:07:12+0000 iVUADAYyor [info] end of checkForUpdate() Update to Nextcloud 15.0.5 available. (channel: "stable")<br /><span class="light">Following file will be downloaded automatically:</span> <code class="light">https://download.nextcloud.com/server/releases/nextcloud-15.0.5.zip</code>
2019-03-09T15:07:15+0000 iVUADAYyor [info] updater started
2019-03-09T15:07:15+0000 iVUADAYyor [info] update of code successful.
2019-03-09T15:07:20+0000 iVUADAYyor [info] setMaintenanceMode("false")
2019-03-09T15:07:20+0000 iVUADAYyor [info] configFileName /var/www/nextcloud/updater/../config/config.php
2019-03-09T15:07:20+0000 iVUADAYyor [info] end of setMaintenanceMode()
2019-03-09T15:07:20+0000 iVUADAYyor [info] maintenance mode is disabled

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

<?php
$CONFIG = array (
  'instanceid' => '',
  'passwordsalt' => '',
  'secret' => '',
  'trusted_domains' => 
  array (
    0 => '',
    1 => '',
    2 => '',
  ),
  'datadirectory' => '/var/www/nextcloud/data',
  'overwrite.cli.url' => '',
  'htaccess.RewriteBase' => '/',
  'dbtype' => 'mysql',
  'version' => '15.0.4.0',
  'dbname' => '',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => '',
  'dbpassword' => '',
  'installed' => true,
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'mail_from_address' => '',
  'mail_smtpmode' => 'smtp',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_domain' => '',
  'mail_smtpsecure' => 'tls',
  'mail_smtpauth' => 1,
  'mail_smtphost' => '',
  'mail_smtpport' => '',
  'mail_smtpname' => '',
  'mail_smtppassword' => '',
  'maintenance' => false,
  'theme' => '',
  'loglevel' => 2,
  'ldapIgnoreNamingRules' => false,
  'ldapProviderFactory' => 'OCA\\User_LDAP\\LDAPProviderFactory',
  'updater.release.channel' => 'stable',
  'updater.secret' => '',
);

The apache2 error.log is empty and the access log does not show any errors.

Please let me know, if there is anything else you need