ownCloud client fails to synchronize Google-Docs-files from Google Drive external drive

Desktop
1

Expected behaviour

ownCloud server successfully adds Google Drive and its contents as an external drive. When synchronizing with the client all contents should be synchronized.

Actual behaviour

When synchronizing with the client all files created with Google-Docs, Google-Sheets and Google-Slides fail to synchronize. ownCloud client makes synchronization attempts which end up adding the affected files to the "Not Synced" tab, displaying following error message on the "Issue" column:

Broken webserver returning empty content length for non-empty file on resume

Steps to reproduce

  1. Add Google Drive to ownCloud server as external drive
  2. Create a Google-Docs, Google-Sheets or Google-Slides file within Google Drive
  3. ownCloud server will synchronize the file, which will be visible on the ownCloud web interface
  4. Add the Google Drive directory to the ownCloud desktop client

Server configuration

Operating system: Ubuntu Server 16.04.3

Web server: Apache/2.4.18

Database: MySql 5.7.21

PHP version: PHP 7.0.28

ownCloud version: 10.0.7.2

Storage backend (external storage): Google Drive

Client configuration

Client version: 2.4.1

Operating system: Ubuntu 16.04.4 LTS

OS language: English

Qt version used by client package (Linux only, see also Settings dialog): 5.6.2

Client package (From ownCloud or distro) (Linux only): distro

Installation path of client: /opt/ownCloud

Logs

  1. Client error log

    "https://owncloud.url/remote.php/dav/files/User/GoogleDrive" has X-Request-ID "43e52526-85da-4b6d-bcf6-b2babfa7df51"
    03-21 13:27:46:322 [ info sync.networkjob ]: OCC::RequestEtagJob created for "https://owncloud.url" + "/GoogleDrive" "OCC::Folder"
    03-21 13:27:47:470 [ info sync.networkjob.etag ]: Request Etag of QUrl("https://owncloud.url/remote.php/dav/files/User/GoogleDrive") FINISHED WITH STATUS QNetworkReply::NetworkError(NoError) ""

  2. Web server error log:

    [Wed Mar 21 13:19:13.465969 2018] [authz_core:error] [pid 21695] [client 92.230.128.158:60118] AH01630: client denied by server configuration: /var/www/owncloud/data/htaccesstest.txt

  3. Server logfile: ownCloud log (data/owncloud.log):

    https://goo.gl/HYe91f