So, subject says everything. I think it is permissions under which PHP script is running (editor1). Somehow it has not enough right?

root@host1 /var/customers/webs/editor1 # ls -Al
total 44
drwxr-xr-x  2 editor1 editor1 4096 Oct 14 16:15 mydomain-1.com
drwxr-xr-x  2 editor1 editor1 4096 Oct 14 16:15 mydomain-2.com
drwxr-xr-x  2 editor1 editor1 4096 Oct 14 16:15 mydomain-3.com
-rw-r--r--  1 editor1 editor1 6422 Aug 20 09:49 index.html

root@host1 /var/customers/webs/editor1 # cd ./mydomain-1.com
root@host1 /var/customers/webs/editor1/mydomain-1.com # ls -Al
total 232
-rw-r--r--  1 www-data www-data   665 Oct  8 17:08 .htaccess
-rw-r--r--  1 www-data www-data 10918 Oct  8 17:08 index.html.bak
-rw-r--r--  1 www-data www-data   405 Oct  8 17:08 index.php
-rw-r--r--  1 www-data www-data 19915 Oct  8 17:08 license.txt
-rw-r--r--  1 www-data www-data  7346 Oct  8 17:08 readme.html
-rw-r--r--  1 www-data www-data  7165 Oct  8 17:08 wp-activate.php
drwxr-xr-x  9 www-data www-data  4096 Oct  8 17:08 wp-admin
-rw-r--r--  1 www-data www-data   351 Oct  8 17:08 wp-blog-header.php
-rw-r--r--  1 www-data www-data  2328 Oct  8 17:08 wp-comments-post.php
-rw-r--r--  1 www-data www-data  3004 Oct  8 17:08 wp-config-sample.php
-rw-r--r--  1 www-data www-data  3207 Oct  8 17:08 wp-config.php
drwxr-xr-x 10 www-data www-data  4096 Oct 14 10:01 wp-content
-rw-r--r--  1 www-data www-data  3939 Oct  8 17:08 wp-cron.php
drwxr-xr-x 25 www-data www-data 12288 Oct  8 17:08 wp-includes
-rw-r--r--  1 www-data www-data  2496 Oct  8 17:08 wp-links-opml.php
-rw-r--r--  1 www-data www-data  3900 Oct  8 17:08 wp-load.php
-rw-r--r--  1 www-data www-data 45463 Oct  8 17:08 wp-login.php
-rw-r--r--  1 www-data www-data  8509 Oct  8 17:08 wp-mail.php
-rw-r--r--  1 www-data www-data 22297 Oct  8 17:08 wp-settings.php
-rw-r--r--  1 www-data www-data 31693 Oct  8 17:08 wp-signup.php
-rw-r--r--  1 www-data www-data  4747 Oct  8 17:08 wp-trackback.php
-rw-r--r--  1 www-data www-data  3236 Oct  8 17:08 xmlrpc.php

Any ideas how to host WordPress a better way? Or how to fix it?

Well, just take a look at the owner, chown it to user/group editor1

10 minutes ago, d00p said:

chown it to user/group editor1

One more beer to this great gentlemen! 🍺

Thank you a lot!