Can't access Nextcloud instance via web browser

Nextcloud version: 16.0.5snap1 (16.0.5.1)
Operating system and version: Ubuntu Server 18.04.3
Apache or nginx version: Apache 2.4
PHP version: PHP 7.2

After upgrading to version 16.0.5.1 (snap version), I can’t access my Nextcloud instance via web browser. The desktop and mobile clients have kept on synchronizing changes to my server, but I’m unable to access the instance on any web browser:

This is the first time this has happened.

This problem has already been reported on GitHub, but no solution has been found yet.

This is the output of my config.php

<?php
$CONFIG = array (
  'apps_paths' => 
  array (
    0 => 
    array (
      'path' => '/snap/nextcloud/current/htdocs/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 => 
    array (
      'path' => '/var/snap/nextcloud/current/nextcloud/extra-apps',
      'url' => '/extra-apps',
      'writable' => true,
    ),
  ),
  'supportedDatabases' => 
  array (
    0 => 'mysql',
  ),
  'memcache.locking' => '\\OC\\Memcache\\Redis',
  'memcache.local' => '\\OC\\Memcache\\Redis',
  'redis' => 
  array (
    'host' => '/tmp/sockets/redis.sock',
    'port' => 0,
  ),
  'passwordsalt' => '[REMOVED]',
  'secret' => '[REMOVED]',
  'trusted_domains' => 
  array (
    0 => 'localhost',
    1 => '[REMOVED]',
  ),
  'datadirectory' => '/var/snap/nextcloud/common/nextcloud/data',
  'overwrite.cli.url' => 'http://localhost',
  'dbtype' => 'mysql',
  'version' => '16.0.5.1',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost:/tmp/sockets/mysql.sock',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => '[REMOVED]',
  'dbpassword' => '[REMOVED]',
  'installed' => true,
  'instanceid' => '[REMOVED]',
  'mail_smtpmode' => 'php',
  'mail_smtpauthtype' => 'LOGIN',
  'maintenance' => false,
  'loglevel' => 2,
  'theme' => '',
  'app_install_overwrite' => 
  array (
    0 => 'mail',
    1 => 'spreed',
    2 => 'files_reader',
  ),
);

And this are the two Apache error logs that I could find in /var/snap/nextcloud/current/apache/logs:

In error_log

[Tue Oct 01 06:25:34.316819 2019] [mpm_event:notice] [pid 2512:tid 140650414647168] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 06:26:13.091621 2019] [ssl:warn] [pid 2531:tid 139652508518272] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 06:26:13.104876 2019] [ssl:warn] [pid 2531:tid 139652508518272] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 06:26:13.106960 2019] [mpm_event:notice] [pid 2531:tid 139652508518272] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 06:26:13.107015 2019] [core:notice] [pid 2531:tid 139652508518272] AH00094: Command line: 'httpd -d /snap/nextcloud/16232 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 06:26:13.114518 2019] [unixd:alert] [pid 2532:tid 139652508518272] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 06:26:13.114989 2019] [unixd:alert] [pid 2534:tid 139652508518272] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 06:26:13.115273 2019] [unixd:alert] [pid 2533:tid 139652508518272] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:28:01.187375 2019] [unixd:alert] [pid 7737:tid 139652508518272] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:42:41.910969 2019] [mpm_event:notice] [pid 2531:tid 139652508518272] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 07:43:19.001390 2019] [ssl:warn] [pid 2516:tid 139956627289984] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 07:43:19.010812 2019] [ssl:warn] [pid 2516:tid 139956627289984] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 07:43:19.012838 2019] [mpm_event:notice] [pid 2516:tid 139956627289984] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 07:43:19.012896 2019] [core:notice] [pid 2516:tid 139956627289984] AH00094: Command line: 'httpd -d /snap/nextcloud/16232 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 07:43:19.020757 2019] [unixd:alert] [pid 2518:tid 139956627289984] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:43:19.021234 2019] [unixd:alert] [pid 2517:tid 139956627289984] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:43:19.021584 2019] [unixd:alert] [pid 2519:tid 139956627289984] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:44:38.305044 2019] [unixd:alert] [pid 3044:tid 139956627289984] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:59:01.251587 2019] [mpm_event:notice] [pid 2516:tid 139956627289984] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 07:59:29.297693 2019] [ssl:warn] [pid 5955:tid 140361952225152] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 07:59:29.306466 2019] [ssl:warn] [pid 5955:tid 140361952225152] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 07:59:29.307930 2019] [mpm_event:notice] [pid 5955:tid 140361952225152] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 07:59:29.307990 2019] [core:notice] [pid 5955:tid 140361952225152] AH00094: Command line: 'httpd -d /snap/nextcloud/16309 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 07:59:29.314150 2019] [unixd:alert] [pid 5957:tid 140361952225152] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:59:29.315376 2019] [unixd:alert] [pid 5956:tid 140361952225152] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 07:59:29.315748 2019] [unixd:alert] [pid 5958:tid 140361952225152] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:00:21.505694 2019] [mpm_event:notice] [pid 5955:tid 140361952225152] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 08:00:57.197023 2019] [ssl:warn] [pid 2520:tid 140384394807168] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 08:00:57.207396 2019] [ssl:warn] [pid 2520:tid 140384394807168] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 08:00:57.208959 2019] [mpm_event:notice] [pid 2520:tid 140384394807168] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 08:00:57.209007 2019] [core:notice] [pid 2520:tid 140384394807168] AH00094: Command line: 'httpd -d /snap/nextcloud/16309 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 08:00:57.215322 2019] [unixd:alert] [pid 2523:tid 140384394807168] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:00:57.215773 2019] [unixd:alert] [pid 2524:tid 140384394807168] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:00:57.216181 2019] [unixd:alert] [pid 2525:tid 140384394807168] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:01:26.870409 2019] [unixd:alert] [pid 2950:tid 140384394807168] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:08:03.755888 2019] [mpm_event:notice] [pid 2520:tid 140384394807168] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 08:08:38.980067 2019] [ssl:warn] [pid 2502:tid 140157572024192] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 08:08:38.990331 2019] [ssl:warn] [pid 2502:tid 140157572024192] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 08:08:38.992141 2019] [mpm_event:notice] [pid 2502:tid 140157572024192] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 08:08:38.992192 2019] [core:notice] [pid 2502:tid 140157572024192] AH00094: Command line: 'httpd -d /snap/nextcloud/16309 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 08:08:39.001540 2019] [unixd:alert] [pid 2504:tid 140157572024192] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:08:39.002142 2019] [unixd:alert] [pid 2505:tid 140157572024192] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:08:39.002648 2019] [unixd:alert] [pid 2506:tid 140157572024192] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:08:40.995811 2019] [unixd:alert] [pid 2788:tid 140157572024192] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:34:23.319987 2019] [mpm_event:notice] [pid 2502:tid 140157572024192] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 08:35:00.832933 2019] [ssl:warn] [pid 2510:tid 140083563513728] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 08:35:00.843814 2019] [ssl:warn] [pid 2510:tid 140083563513728] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 08:35:00.845211 2019] [mpm_event:notice] [pid 2510:tid 140083563513728] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 08:35:00.845263 2019] [core:notice] [pid 2510:tid 140083563513728] AH00094: Command line: 'httpd -d /snap/nextcloud/16309 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 08:35:00.853328 2019] [unixd:alert] [pid 2513:tid 140083563513728] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:35:00.853920 2019] [unixd:alert] [pid 2511:tid 140083563513728] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:35:00.854325 2019] [unixd:alert] [pid 2512:tid 140083563513728] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:35:28.683962 2019] [unixd:alert] [pid 2932:tid 140083563513728] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:39:07.333007 2019] [mpm_event:notice] [pid 2510:tid 140083563513728] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 08:39:36.772406 2019] [ssl:warn] [pid 4993:tid 139716068394880] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 08:39:36.781120 2019] [ssl:warn] [pid 4993:tid 139716068394880] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 08:39:36.782604 2019] [mpm_event:notice] [pid 4993:tid 139716068394880] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 08:39:36.782645 2019] [core:notice] [pid 4993:tid 139716068394880] AH00094: Command line: 'httpd -d /snap/nextcloud/16232 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 08:39:36.790632 2019] [unixd:alert] [pid 4995:tid 139716068394880] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:39:36.791107 2019] [unixd:alert] [pid 4994:tid 139716068394880] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:39:36.791467 2019] [unixd:alert] [pid 4996:tid 139716068394880] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:40:07.840603 2019] [unixd:alert] [pid 6434:tid 139716068394880] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:41:07.931435 2019] [mpm_event:notice] [pid 4993:tid 139716068394880] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 08:41:47.061072 2019] [ssl:warn] [pid 2532:tid 139821922461568] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 08:41:47.070053 2019] [ssl:warn] [pid 2532:tid 139821922461568] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 08:41:47.071443 2019] [mpm_event:notice] [pid 2532:tid 139821922461568] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 08:41:47.071480 2019] [core:notice] [pid 2532:tid 139821922461568] AH00094: Command line: 'httpd -d /snap/nextcloud/16232 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 08:41:47.079398 2019] [unixd:alert] [pid 2535:tid 139821922461568] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:41:47.079887 2019] [unixd:alert] [pid 2533:tid 139821922461568] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:41:47.080161 2019] [unixd:alert] [pid 2534:tid 139821922461568] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 08:41:48.078891 2019] [unixd:alert] [pid 2670:tid 139821922461568] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 09:10:03.328274 2019] [proxy_fcgi:error] [pid 2535:tid 139821586511616] [client 82.102.27.124:32874] AH01067: Failed to read FastCGI header
[Tue Oct 01 09:10:03.467190 2019] [proxy_fcgi:error] [pid 2535:tid 139821586511616] (104)Connection reset by peer: [client 82.102.27.124:32874] AH01075: Error dispatching request to : 
[Tue Oct 01 09:10:05.526015 2019] [mpm_event:notice] [pid 2532:tid 139821922461568] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 09:10:54.972450 2019] [ssl:warn] [pid 2548:tid 139708317996928] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 09:10:55.003420 2019] [ssl:warn] [pid 2548:tid 139708317996928] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 09:10:55.007834 2019] [mpm_event:notice] [pid 2548:tid 139708317996928] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 09:10:55.007886 2019] [core:notice] [pid 2548:tid 139708317996928] AH00094: Command line: 'httpd -d /snap/nextcloud/16232 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 09:10:55.028155 2019] [unixd:alert] [pid 2550:tid 139708317996928] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 09:10:55.028408 2019] [unixd:alert] [pid 2552:tid 139708317996928] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 09:10:55.028605 2019] [unixd:alert] [pid 2551:tid 139708317996928] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 09:11:07.022894 2019] [unixd:alert] [pid 2953:tid 139708317996928] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 10:32:20.382254 2019] [mpm_event:notice] [pid 2548:tid 139708317996928] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 10:33:06.173230 2019] [ssl:warn] [pid 2491:tid 140396492072832] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 10:33:06.184759 2019] [ssl:warn] [pid 2491:tid 140396492072832] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 10:33:06.186176 2019] [mpm_event:notice] [pid 2491:tid 140396492072832] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 10:33:06.186224 2019] [core:notice] [pid 2491:tid 140396492072832] AH00094: Command line: 'httpd -d /snap/nextcloud/16232 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 10:33:06.193042 2019] [unixd:alert] [pid 2492:tid 140396492072832] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 10:33:06.193568 2019] [unixd:alert] [pid 2493:tid 140396492072832] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 10:33:06.193944 2019] [unixd:alert] [pid 2494:tid 140396492072832] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 10:33:25.597427 2019] [unixd:alert] [pid 2899:tid 140396492072832] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 15:28:11.762567 2019] [mpm_event:notice] [pid 2491:tid 140396492072832] AH00491: caught SIGTERM, shutting down
[Tue Oct 01 15:28:49.744700 2019] [ssl:warn] [pid 2498:tid 140465550735232] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
[Tue Oct 01 15:28:49.755931 2019] [ssl:warn] [pid 2498:tid 140465550735232] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Tue Oct 01 15:28:49.757544 2019] [mpm_event:notice] [pid 2498:tid 140465550735232] AH00489: Apache/2.4.41 (Unix) OpenSSL/1.0.2g configured -- resuming normal operations
[Tue Oct 01 15:28:49.757590 2019] [core:notice] [pid 2498:tid 140465550735232] AH00094: Command line: 'httpd -d /snap/nextcloud/16232 -D EnableHTTPS -D EnableHSTS -D FOREGROUND'
[Tue Oct 01 15:28:49.765330 2019] [unixd:alert] [pid 2501:tid 140465550735232] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 15:28:49.765815 2019] [unixd:alert] [pid 2500:tid 140465550735232] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 15:28:49.766212 2019] [unixd:alert] [pid 2502:tid 140465550735232] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 15:50:17.363399 2019] [unixd:alert] [pid 4416:tid 140465550735232] AH02155: getpwuid: couldn't determine user name from uid 4294967295, you probably need to modify the User directive
[Tue Oct 01 16:30:17.369871 2019] [proxy_fcgi:error] [pid 2501:tid 140465303160576] (70008)Partial results are valid but processing is incomplete: [client 179.15.238.241:58488] AH01075: Error dispatching request to : (reading input brigade)

And php_errors.log

Stack trace:
#0 /snap/nextcloud/15565/htdocs/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(429): OC\DB\Connection->connect()
#1 /snap/nextcloud/15565/htdocs/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(389): Doctrine\DBAL\Connection->getDatabasePlatformVersion()
#2 /snap/nextcloud/15565/htdocs/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(328): Doctrine\DBAL\Connection->detectDatabasePlatform()
#3 /snap/nextcloud/15565/htdocs/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(623): Doctrine\DBAL\Connection->getDatabasePlatform()
#4 /snap/nextcloud/15565/htdocs/lib/private/DB/Connection.php(151): Doctrine\DBAL\Connection->setTransactionIsolation(2)
#5 /snap/nextcloud/15565/htdocs/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/DriverManager.php(172): OC\DB\Connection in /snap/nextcloud/15565/htdocs/lib/private/DB/Connection.php on line 64

I’m not sure if any of you guys have an idea of how to solve this.

Thanks in advance for all your help.

Доброе время суток! У меня такая же проблема. Вам удалось решить ее?