I was messing with a 'de' (german) part of a 'dk' ,'en' and 'de' setup .. but it ended up with the below error .. I have restored everything on a plesk backup asp.net setup, but this error stil show:

[ArgumentNullException: Value cannot be null.
Parameter name: value]
   System.Web.Caching.CacheEntry..ctor(String key, Object value, CacheDependency dependency, CacheItemRemovedCallback onRemovedHandler, DateTime utcAbsoluteExpiration, TimeSpan slidingExpiration, CacheItemPriority priority, Boolean isPublic) +8840091
   System.Web.Caching.CacheInternal.DoInsert(Boolean isPublic, String key, Object value, CacheDependency dependencies, DateTime utcAbsoluteExpiration, TimeSpan slidingExpiration, CacheItemPriority priority, CacheItemRemovedCallback onRemoveCallback, Boolean replace) +93
   System.Web.Caching.Cache.Add(String key, Object value, CacheDependency dependencies, DateTime absoluteExpiration, TimeSpan slidingExpiration, CacheItemPriority priority, CacheItemRemovedCallback onRemoveCallback) +81
   umbraco.cms.businesslogic.cache.Cache.GetCacheItem(String cacheKey, Object syncLock, CacheItemPriority priority, CacheItemRemovedCallback refreshAction, CacheDependency cacheDependency, TimeSpan timeout, GetCacheItemDelegate`1 getCacheItem) +250
   umbraco.cms.businesslogic.language.Language..ctor(Int32 id) +223
   umbraco.cms.businesslogic.web.Domain.initDomain(Int32 id) +179
   umbraco.cms.businesslogic.web.Domain.<GetDomains>b__0() +218
   umbraco.cms.businesslogic.cache.Cache.GetCacheItem(String cacheKey, Object syncLock, CacheItemPriority priority, CacheItemRemovedCallback refreshAction, CacheDependency cacheDependency, TimeSpan timeout, GetCacheItemDelegate`1 getCacheItem) +114
   umbraco.cms.businesslogic.web.Domain.GetDomains() +153
   umbraco.cms.businesslogic.web.Domain.GetDomain(String DomainName) +45
   umbraco.cms.businesslogic.web.Domain.Exists(String DomainName) +5
   umbraco.requestHandler.CreateXPathQuery(String url, Boolean checkDomain) +155
   umbraco.requestHandler..ctor(XmlDocument _umbracoContent, String url) +407
   umbraco.UmbracoDefault.Page_PreInit(Object sender, EventArgs e) +728
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.EventHandler.Invoke(Object sender, EventArgs e) +0
   System.Web.UI.Page.OnPreInit(EventArgs e) +8698174
   System.Web.UI.Page.PerformPreInit() +31
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +282