Hey there,

I am really sorry for the delay of this reply as it is a weekend for us here.

I've tried to open your backend Easyblog dashboard page but i hitting following error :

<b>Warning</b>:  require_once(/var/www/web190/html/BSG_neu/administrator/plugins/system/bt_shortcode_system/shortcode/core/generator.php): failed to open stream: No such file or directory in <b>/var/www/web190/html/BSG_neu/plugins/content/bt_shortcode_content/bt_shortcode_content.php</b> on line <b>8</b><br />

<br />

<b>Fatal error</b>:  require_once(): Failed opening required '/var/www/web190/html/BSG_neu/administrator/plugins/system/bt_shortcode_system/shortcode/core/generator.php' (include_path='.:/opt/php/5.6.26/share/pear') in <b>/var/www/web190/html/BSG_neu/plugins/content/bt_shortcode_content/bt_shortcode_content.php</b> on line <b>8</b><br />

Then I try to disable this plugin "Content - BT Shortcode", it seems like save article post it work fine now.

Regarding with your registration page, currently I have no ideas yet because it work fine if that is Joomla registration default page (http://www.bsg-aw.de/index.php?option=com_users&view=registration), may i know which component generate this registration page? Because if click on the registration link from the login pop up, it will show blank page.