Webdav has been reporting an error

Nextcloud version 15.0.6:
Operating system and version ubuntu18.04:
Apache or nginx version nginx:
PHP version (eg, 7.1):

The issue you are facing:

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

Steps to replicate it:

  1. Always exist

The output of your Nextcloud log in Admin > Logging:

[webdav] Fatal: Sabre\DAV\Exception\ServiceUnavailable: Could not open file at <<closure>>

0. /var/www/html/3rdparty/sabre/dav/lib/DAV/CorePlugin.php line 85
   get()
1. <<closure>>
   httpGet(Sabre\HTTP\Reque ... "}, Sabre\HTTP\Response {})
2. /var/www/html/3rdparty/sabre/event/lib/EventEmitterTrait.php line 105
   call_user_func_array([Sabre\DAV\CorePlugin {},"httpGet"], [Sabre\HTTP\Requ ... }])
3. /var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php line 479
   emit("method:GET", [Sabre\HTTP\Requ ... }])
4. /var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php line 254
   invokeMethod(Sabre\HTTP\Reque ... "}, Sabre\HTTP\Response {})
5. /var/www/html/apps/dav/lib/Server.php line 301
   exec()
6. /var/www/html/apps/dav/appinfo/v2/remote.php line 35
   exec()
7. /var/www/html/remote.php line 163
   require_once("/var/www/html/a ... p")

GET /remote.php/dav/files/likeyi/%E7%A7%81%E6%9C%89%E4%BA%91%E5%8F%8D%E9%A6%88.docx
from 219.147.8.238 by likeyi at 2019-04-11T01:31:15+00:00

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

<?php
$CONFIG = array (
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'apps_paths' =>
  array (
    0 =>
    array (
      'path' => '/var/www/html/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 =>
    array (
      'path' => '/var/www/html/custom_apps',
      'url' => '/custom_apps',
      'writable' => true,
    ),
  ),
  'instanceid' => 'oc25ikasdia9s3i',
  'passwordsalt' => 'xxadcd0KDSvTBSx7YUGRNLikRCz32',
  'secret' => 'CIi9hdepNR15asas+oSFQ362jet5GF5IuBraQH4FeWr/IfyJ',
  'trusted_domains' =>
  array (
    0 => 'xxxxx:6111',
    1 => 'nginx-server-',
  ),
  'datadirectory' => '/var/www/html/data',
  'dbtype' => 'mysql',
  'version' => '15.0.6.1',
  'overwrite.cli.url' => 'https://xxxxx.cn:6111',
  'dbname' => 'nextcloud',
  'dbhost' => 'db',
  'dbport' => '',
  'dbtableprefix' => '',
  'mysql.utf8mb4' => true,
  'dbuser' => 'nextcloud',
  'dbpassword' => 'xxxxxx',
  'installed' => true,
  'onlyoffice' =>
  array (
    'DocumentServerUrl' => '/ds-vpath/',
    'DocumentServerInternalUrl' => 'http://onlyoffice-document-server/',
    'StorageUrl' => 'http://nginx-server-jask/',
  ),
  'force_language' => 'zh_CN',
  'force_locale' => 'zh_CN',
  'knowledgebaseenabled' => false,
  'allow_user_to_change_display_name' => false,
  'skeletondirectory' => '',
  'maintenance' => false,
  'loglevel' => 2,
);

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

"PROPFIND /remote.php/dav/files/likeyi/%E6%95%B0%E6%8D%AE HTTP/2.0" 207 386 "-" "Mozilla/5.0 (Windows) mirall/2.5.1final (build 20181204) (Nextcloud)" "-"
 - [11/Apr/2019:09:34:43 +0800] "PROPFIND /remote.php/dav/files/likeyi/%E6%AF%8F%E5%91%A8%E6%AC%A0%E6%AC%BE%E6%B1%87%E6%80%BB HTTP/2.0" 207 422 "-" "Mozilla/5.0 (Windows) mirall/2.5.1final (build 20181204) (Nextcloud)" "-"
 

This usually means that the file access rights are not correctly set on the console. Make sure that the user under which the web server is running, e.g. www-data, can access the file.

Is this the reason for the web server setup?

Sorry, I don’t understand what you want to tell me with this question and the screenshot?!
Files are usually stored in a sub directory of ./data/<user>/files. That’s the place where you should check the file permissions of the file in question.