We had a working installation till a few days back, but suddenly its showing the following error screen on loading content tree. The error is same for all content trees (content/media etc) Any ideas on how to tackle this?
Object reference not set to an instance of an object.
Stack trace
at Umbraco.Cms.Web.Configuration.UmbracoSettings.<get_Trees>b__f(ITree x) at System.Linq.Set`1.InternalGetHashCode(TElement value) at System.Linq.Set`1.Find(TElement value, Boolean add) at System.Linq.Enumerable.<DistinctIterator>d__81`1.MoveNext() at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext() at System.Linq.Buffer`1..ctor(IEnumerable`1 source) at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source) at Umbraco.Cms.Web.Trees.ApplicationTreeController.Index(String appAlias) at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)