Multisite Fatal error

Hello,
I want to generate a multisite (reason is that I need multilanguage) and followed the wordpress instructions.
I changed the wp-config.php and the .htsaccess directly in the Fillezilla.

However now I receive the following error message:

Fatal error: Call to undefined function wp_get_current_user() in /homepages/18/d317155877/htdocs/clickandbuilds/WordPress/Chris_Hilfe/wp-includes/capabilities.php on line 424

The site is https://s317155896.online.de/
the .httaccess looks like this:

# BEGIN WordPress
<IfModule mod_rewrite.c>

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ – [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ wp/$1 [L]
RewriteRule . index.php [L]

</IfModule>

# END WordPress

AddHandler x-mapp-php5.5 .php

AddHandler x-mapp-php5.5 .php

the wp-config.php looks like this:

/**
* For developers: WordPress debugging mode.
*
* Change this to true to enable the display of notices during development.
* It is strongly recommended that plugin and theme developers use WP_DEBUG
* in their development environments.
*/
define(‘WP_DEBUG’, false);

/**
* Disable the Plugin and Theme Editor.
*
* Occasionally you may wish to disable the plugin or theme editor to prevent
* overzealous users from being able to edit sensitive files and potentially crash the site.
* Disabling these also provides an additional layer of security if a hacker
* gains access to a well-privileged user account.
*/
define(‘DISALLOW_FILE_EDIT’, true);

/* Multisite */
define( ‘WP_ALLOW_MULTISITE’, true );

define(‘MULTISITE’, true);
define(‘SUBDOMAIN_INSTALL’, true);
define(‘DOMAIN_CURRENT_SITE’, ‘s317155896.online.de’);
define(‘PATH_CURRENT_SITE’, ‘/’);
define(‘SITE_ID_CURRENT_SITE’, 1);
define(‘BLOG_ID_CURRENT_SITE’, 1);

/* That’s all, stop editing! Happy blogging. */

I am not a programmer have only basic knowledge.May be here in this forum is someone who has an advice for me how I could proceed.

Many Thx