Can't access my sub-site dashboard – get an 'HTTP ERROR 500'

Hi I feel I have tried every possible option. I have a WP multisite withe one site on main domain and one site on subdomain withe mapped domain.

But I cant access dashboard on mapeddomain.com/wp-admin – original 2domain.maindomain.com

I have ben working intensively on the site for many days now and the error just came out of nothing.

This is part of my wp-config.php;

/* Multisite */

define( ‘WP_ALLOW_MULTISITE’, true );

define(‘SUNRISE’, ‘on’:wink:;

define(‘MULTISITE’, true);

define(‘SUBDOMAIN_INSTALL’, true);

define(‘DOMAIN_CURRENT_SITE’, ‘mymaindomain.com’:wink:;

define(‘PATH_CURRENT_SITE’, ‘/’:wink:;

define(‘SITE_ID_CURRENT_SITE’, 1);

define(‘BLOG_ID_CURRENT_SITE’, 1);

And this is my .htaccess:

# BEGIN WordPress

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)$ $1 [L]

RewriteRule . index.php [L]

# END WordPress

I hope some of you can help!