First of all sorry for my lack of german.
I also had this problem, but I've got it solved, it cames arround that xsendfile apache extension is not working for you, it can be several things:
First be sure that you have .htaccess enabled in your apache. (in detail: https://httpd.apache.org/docs/2.4/en/howto/htaccess.html)
But as a quickfix add this to your apache vhost config:
<Directory "/var/www/html/ilias">
AllowOverride All
</Directory>
Then you have to tell xsendfile to enable your directories with XSendFilePath param, yours seem fine, but you may have the same problem I had, if you are using symbolic links in your directories, you have to add also an extra XSendFilePath param for your symbolic links.
For instance if your "/var/www/html/ilias" directory points via symbolic link to "/mnt/abigdisk/ilias" you have to add also "XSendFilePath /mnt/abigdisk/ilias" to your config.
If all this fails, there are a some shortcuts you can take to unblock the situation, for instance:
- Disabling xsendfile and using plain old php, not as optimized but it works. In order to do that copy the file Services/FileDelivery/classes/override.php.template to Services/FileDelivery/classes/override.php, and restart apache.
- Enable and configure xsendfile globally, ignoring .htaccess (carefull if you have something else in your apache as you will be enabling xsendfile there too). in order to do that, if you are running ubuntu, just create /etc/apache2/mods-enabled/xsendfile.conf with this content (with your directories):
CitaXSendFile On
XSendFilePath /opt/ilias
XSendFilePath /opt/iliasdata
Good luck
Andrés