Service Temporarily Unavailable, AH01067: Failed to read FastCGI header, Nextcloud auf Ubuntu mit Plesk

Nextcloud version (16/18.04/18.06):
Operating system and version (eg, Ubuntu 16.04):
Apache or nginx version (nginx, 1.16.1):
PHP version (eg, 7.3):
After Log in there is the following message: Service Temporarily Unavailable
It happened just over night. I have different nextcloud instances running but the Problem is on all instances. Also if I install the new nextcloud-version on a new plesk domain, same error. Also with older versions, e.g nextcloud v16.

I alreade restarted my root server, changed php versions, deactivated php handlers, increased different fpm limits, increased FcgidIOTimeout, increased limits in fcgid.conf

I already had support from my hosting company but without succress so far.

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

The output of your Nextcloud log in Admin > Logging:

"reqId":"b8flRK05woRPuLxRjULR","level":0,"time":"2020-07-16T05:44:33+00:00","remoteAddr":"84.227.47.15","user":"--","app":"webdav","method":"PROPFIND","url":"/remote.php/dav/calendars/Peter/calendar-name/","message":{"Exception":"Sabre\\DAV\\Exception\\NotAuthenticated","Message":"No public access to this resource., No 'Authorization: Basic' header found. Either the client didn't send one, or the server is misconfigured, No 'Authorization: Bearer' header found. Either the client didn't send one, or the server is mis-configured, No 'Authorization: Basic' header found. Either the client didn't send one, or the server is misconfigured","Code":0,"Trace":[{"function":"beforeMethod","class":"Sabre\\DAV\\Auth\\Plugin","type":"->","args":[{"absoluteUrl":"https://drive.domain.com/remote.php/dav/calendars/Peter/calendar-name/","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"/var/www/vhosts/domain.com/drive.domain.com/3rdparty/sabre/event/lib/EventEmitterTrait.php","line":105,"function":"call_user_func_array","args":[[{"autoRequireLogin":true,"__class__":"Sabre\\DAV\\Auth\\Plugin"},"beforeMethod"],[{"absoluteUrl":"https://drive.domain.com/remote.php/dav/calendars/Peter/calendar-name/","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]]},{"file":"/var/www/vhosts/domain.com/drive.domain.com/3rdparty/sabre/dav/lib/DAV/Server.php","line":466,"function":"emit","class":"Sabre\\Event\\EventEmitter","type":"->","args":["beforeMethod",[{"absoluteUrl":"https://drive.domain.com/remote.php/dav/calendars/Peter/calendar-name/","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]]},{"file":"/var/www/vhosts/domain.com/drive.domain.com/3rdparty/sabre/dav/lib/DAV/Server.php","line":254,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->","args":[{"absoluteUrl":"https://drive.domain.com/remote.php/dav/calendars/Peter/calendar-name/","__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"/var/www/vhosts/domain.com/drive.domain.com/apps/dav/lib/Server.php","line":319,"function":"exec","class":"Sabre\\DAV\\Server","type":"->","args":[]},{"file":"/var/www/vhosts/domain.com/drive.domain.com/apps/dav/appinfo/v2/remote.php","line":35,"function":"exec","class":"OCA\\DAV\\Server","type":"->","args":[]},{"file":"/var/www/vhosts/domain.com/drive.domain.com/remote.php","line":165,"args":["/var/www/vhosts/domain.com/drive.domain.com/apps/dav/appinfo/v2/remote.php"],"function":"require_once"}],"File":"/var/www/vhosts/domain.com/drive.domain.com/3rdparty/sabre/dav/lib/DAV/Auth/Plugin.php","Line":168,"CustomMessage":"--"},"userAgent":"Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.8.1 Lightning/68.8.1","version":"18.0.6.0"}
{"reqId":"Xw-tNn8AAQEAACpgAhQAAAAB","level":0,"time":"2020-07-16T06:01:26+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tNn8AAQEAACpgAhQAAAAB","level":0,"time":"2020-07-16T06:01:27+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tNn8AAQEAACpgAhQAAAAB","level":0,"time":"2020-07-16T06:01:27+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tNn8AAQEAACpgAhQAAAAB","level":0,"time":"2020-07-16T06:01:27+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tNn8AAQEAACpgAhQAAAAB","level":0,"time":"2020-07-16T06:01:27+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tNn8AAQEAACpgAhQAAAAB","level":0,"time":"2020-07-16T06:01:27+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tNn8AAQEAACpgAhQAAAAB","level":0,"time":"2020-07-16T06:01:27+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"06qrZk8wb32iAUjJGq6o","level":0,"time":"2020-07-16T06:01:32+00:00","remoteAddr":"5.54.69.238","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196301","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"06qrZk8wb32iAUjJGq6o","level":0,"time":"2020-07-16T06:01:32+00:00","remoteAddr":"5.54.69.238","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196301 in 0 seconds","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tR38AAQEAACpgAhoAAAAB","level":0,"time":"2020-07-16T06:01:43+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/?dir=/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tR38AAQEAACpgAhoAAAAB","level":0,"time":"2020-07-16T06:01:43+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/?dir=/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tR38AAQEAACpgAhoAAAAB","level":0,"time":"2020-07-16T06:01:43+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/?dir=/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tR38AAQEAACpgAhoAAAAB","level":0,"time":"2020-07-16T06:01:43+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/?dir=/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tR38AAQEAACpgAhoAAAAB","level":0,"time":"2020-07-16T06:01:43+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/?dir=/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tR38AAQEAACpgAhoAAAAB","level":0,"time":"2020-07-16T06:01:43+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/?dir=/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"Xw-tR38AAQEAACpgAhoAAAAB","level":0,"time":"2020-07-16T06:01:43+00:00","remoteAddr":"5.54.69.238","user":"Nicolas","app":"no app in context","method":"GET","url":"/apps/files/?dir=/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"O8Q5VGMl5xy4dUBCrCLK","level":0,"time":"2020-07-16T06:01:47+00:00","remoteAddr":"5.54.69.238","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196302","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"O8Q5VGMl5xy4dUBCrCLK","level":0,"time":"2020-07-16T06:01:47+00:00","remoteAddr":"5.54.69.238","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196302 in 0 seconds","userAgent":"Mozilla/5.0 (Android 8.1.0; Mobile; rv:68.0) Gecko/68.0 Firefox/68.0","version":"18.0.6.0"}
{"reqId":"4yFCXQ2e8pLLSWJwblT1","level":0,"time":"2020-07-16T06:02:12+00:00","remoteAddr":"84.227.47.15","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196303","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"4yFCXQ2e8pLLSWJwblT1","level":0,"time":"2020-07-16T06:02:12+00:00","remoteAddr":"84.227.47.15","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196303 in 0 seconds","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"A8FQ4xv5NUKRA8u1EcHW","level":0,"time":"2020-07-16T06:05:02+00:00","remoteAddr":"2001:1680:101:4ea::1","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196304","userAgent":"curl/7.47.0","version":"18.0.6.0"}
{"reqId":"A8FQ4xv5NUKRA8u1EcHW","level":0,"time":"2020-07-16T06:05:02+00:00","remoteAddr":"2001:1680:101:4ea::1","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196304 in 0 seconds","userAgent":"curl/7.47.0","version":"18.0.6.0"}
{"reqId":"Xw-2B38AAQEAADxXat8AAAAH","level":0,"time":"2020-07-16T06:39:03+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2B38AAQEAADxXat8AAAAH","level":0,"time":"2020-07-16T06:39:03+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2B38AAQEAADxXat8AAAAH","level":0,"time":"2020-07-16T06:39:03+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2B38AAQEAADxXat8AAAAH","level":0,"time":"2020-07-16T06:39:03+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2B38AAQEAADxXat8AAAAH","level":0,"time":"2020-07-16T06:39:03+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2B38AAQEAADxXat8AAAAH","level":0,"time":"2020-07-16T06:39:03+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2B38AAQEAADxXat8AAAAH","level":0,"time":"2020-07-16T06:39:03+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/apps/files/","message":"Deprecated event type for OCA\\Files::loadAdditionalScripts: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"loYKKsMtLLmfhfD1QbPC","level":0,"time":"2020-07-16T06:39:06+00:00","remoteAddr":"178.197.236.74","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196305","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"loYKKsMtLLmfhfD1QbPC","level":0,"time":"2020-07-16T06:39:06+00:00","remoteAddr":"178.197.236.74","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196305 in 0 seconds","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2FX8AAQEAADxi-asAAAAI","level":0,"time":"2020-07-16T06:39:18+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/settings/apps","message":"Deprecated event type for \\OCP\\Files::preWrite: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2FX8AAQEAADxi-asAAAAI","level":0,"time":"2020-07-16T06:39:18+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/settings/apps","message":"Deprecated event type for \\OCP\\Files::postWrite: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"lpXdpGMpuzrtLYM0LImH","level":0,"time":"2020-07-16T06:39:20+00:00","remoteAddr":"178.197.236.74","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196306","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"lpXdpGMpuzrtLYM0LImH","level":0,"time":"2020-07-16T06:39:20+00:00","remoteAddr":"178.197.236.74","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196306 in 0 seconds","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2GH8AAQEAADxMMCYAAAAE","level":0,"time":"2020-07-16T06:39:20+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/settings/apps/categories","message":"Deprecated event type for \\OCP\\Files::preWrite: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"Xw-2GH8AAQEAADxMMCYAAAAE","level":0,"time":"2020-07-16T06:39:20+00:00","remoteAddr":"178.197.236.74","user":"Peter","app":"no app in context","method":"GET","url":"/settings/apps/categories","message":"Deprecated event type for \\OCP\\Files::postWrite: Symfony\\Component\\EventDispatcher\\GenericEvent","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"5fr0ufNUwjcIudGehwxP","level":0,"time":"2020-07-16T06:39:42+00:00","remoteAddr":"178.197.236.74","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196307","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"5fr0ufNUwjcIudGehwxP","level":0,"time":"2020-07-16T06:39:42+00:00","remoteAddr":"178.197.236.74","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196307 in 0 seconds","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0","version":"18.0.6.0"}
{"reqId":"gF2Hfk1wNv1YlXeHyKhs","level":0,"time":"2020-07-16T07:05:01+00:00","remoteAddr":"2001:1680:101:4ea::1","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Run OC\\Command\\CommandJob job with ID 196308","userAgent":"curl/7.47.0","version":"18.0.6.0"}
{"reqId":"gF2Hfk1wNv1YlXeHyKhs","level":0,"time":"2020-07-16T07:05:01+00:00","remoteAddr":"2001:1680:101:4ea::1","user":"--","app":"cron","method":"GET","url":"/cron.php","message":"Finished OC\\Command\\CommandJob job with ID 196308 in 0 seconds","userAgent":"curl/7.47.0","version":"18.0.6.0"}

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

<?php
$CONFIG = array (
  'instanceid' => 'oclbbmhfav4t',
  'passwordsalt' => '...',
  'secret' => '...',
  'trusted_domains' => 
  array (
    0 => '...',
  ),
  'datadirectory' => '...',
  'overwrite.cli.url' => '...',
  'dbtype' => 'mysql',
  'version' => '18.0.6.0',
  'dbname' => '...',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => '...',
  'dbpassword' => '...',
  'installed' => true,
  'loglevel' => 0,
  'maintenance' => false,
  'theme' => '',
  'updater.release.channel' => 'stable',
  'skeletondirectory' => '',
  'mail_smtpmode' => 'smtp',
  'mail_from_address' => 'cloud',
  'mail_domain' => '...',
  'mail_smtphost' => '...',
  'htaccess.RewriteBase' => '/',
  'memcache.distributed' => '\\OC\\Memcache\\Redis',
  'memcache.local' => '\\OC\\Memcache\\Redis',
  'memcache.locking' => '\\OC\\Memcache\\Redis',
  'redis' => 
  array (
    'host' => 'localhost',
    'port' => 6379,
  ),
  'versions_retention_obligation' => 'auto',
  'app_install_overwrite' => 
  array (
    0 => 'calendar',
  ),
  'mail_sendmailmode' => 'smtp',
  'mail_smtpport' => '25',
  'mail_smtpauth' => 1,
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtpsecure' => 'tls',
  'mail_smtpname' => '...',
  'mail_smtppassword' => '...',
);

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

1. AH01067: Failed to read FastCGI header
2. (104)Connection reset by peer: AH01075: Error dispatching request to : 

nginx-Error

13646#0: *2416 recv() failed (104: Connection reset by peer) while reading response header from upstream

I am also still waiting for a solution.
It has nothing todo with Plesk, AFAICS, but with PHP 7.3.20, which was rolled out by Plesk this week.

See also:

Great, thank you very much - as Plesk did it automatically I was not aware that this was what have been changed…so many hours of analyis…now I know more :slight_smile:

Good to find this, I’ve been debugging for a few hours over several days as well and only just found this post, is anyone aware if Plesk is aware of this?

I’ve seen this ‘Talk’ post, but nothing from Plesk themselfs (yet):