vvtv

Thank you for response!
The server is Apache 2.4.6 on CentOS 7.1.1503, PHP Version 5.4.16, wordpress 4.6.1
There are couple of wordpress plugins installed (below is the list, but nothing is really used – wordpress is in test mode and while this ‘skip head!’ error is cluttering log file I don’t see how it can be used in production mode)

Akismet (Inactive)
Version 3.2

Aqua Page Builder (Inactive)
Version 1.1.5

Easy SMTP Mail (Active)
Version 1.7

Easy Updates Manager (Active)
Version 6.2.3

Front-end Editor (Inactive)
Version 2.3.1

Hello Dolly (Inactive)
Version 1.6

Jetpack by WordPress.com (Inactive)
Version 4.3.1

Live Composer (Active)
Version 1.2.4.1

Media File Manager (Active)
Version 1.4.2

MiniMax – Page Layout Builder (Inactive)
Version 2.0.3

NextScripts: Social Networks Auto-Poster (Active)
Version 3.7.3

Page Builder by SiteOrigin (Active)
Version 2.4.16

SiteOrigin CSS (Active)
Version 1.1.1

SiteOrigin Widgets Bundle (Active)
Version 1.7.1

Spider Video Player (Inactive)
Version 1.5.18

Super Socializer (Active)
Version 7.8

SVG Support (Active)
Version 2.2.3.2

WP Super Edit (Inactive)
Version 2.5.2

WPide (Active)
Version 2.3.2

xfile (Active)
simple file manger
Version 1.0