I moved my umbraco installation, which was working fine, to a new server.

The new server runs IIS7.5 on windows 2008 server.

The first problem i came across was that access to /App_Data/umbraco.config was denied.

So i used procmon.exe to establish that the app pool identity was trying to access this file that it didnt have write permissions for.  So i gave the app pool the correct permissions (read on the root folder, write on app_data plus all sub dirs + files) but i still got the same problem.

eventually i tried giving app pool identity write access on the root directory and everything below it - this worked, and it deleted the umbraco.config, and now gives me this error...

[NullReferenceException: Object reference not set to an instance of an object.]
   umbraco.cms.businesslogic.web.Domain.<GetDomains>b__0() +84
   umbraco.cms.businesslogic.cache.Cache.GetCacheItem(String cacheKey, Object syncLock, CacheItemPriority priority, CacheItemRemovedCallback refreshAction, CacheDependency cacheDependency, TimeSpan timeout, GetCacheItemDelegate`1 getCacheItem) +132
   umbraco.cms.businesslogic.web.Domain.GetDomains() +158
   umbraco.cms.businesslogic.web.Domain.GetDomain(String DomainName) +44
   umbraco.requestHandler.CreateXPathQuery(String url, Boolean checkDomain) +232
   umbraco.requestHandler..ctor(XmlDocument umbracoContent, String url) +523
   umbraco.UmbracoDefault.Page_PreInit(Object sender, EventArgs e) +1062
   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) +8876158
   System.Web.UI.Page.PerformPreInit() +31
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +328