When I was adding a new page to my website when this happened...

Does any one know what happened?

An error has occurred.
DotNetNuke.Services.Exceptions.PageLoadException: Value cannot be null. Parameter name: type ---> System.ArgumentNullException: Value cannot be null. Parameter name: type at System.Activator.CreateInstance(Type type, Boolean nonPublic) at DotNetNuke.Framework.Reflection.CreateObject(String TypeName, String CacheKey, Boolean UseCache) at DotNetNuke.Framework.Reflection.CreateObject(String ObjectProviderType, String ObjectProviderName, String ObjectNamespace, String ObjectAssemblyName, Boolean UseCache) at DotNetNuke.Modules.NavigationProvider.NavigationProvider.Instance(String FriendlyName) at DotNetNuke.UI.Skins.NavObjectBase.InitializeNavControl(Control objParent, String strDefaultProvider) at DotNetNuke.UI.Skins.Controls.TreeViewMenu.OnInit(EventArgs e) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Control.AddedControl(Control control, Int32 index) at System.Web.UI.ControlCollection.Add(Control child) at DotNetNuke.Framework.DefaultPage.Page_Init(Object sender, EventArgs e) at System.Web.UI.Control.OnInit(EventArgs e) at System.Web.UI.Page.OnInit(EventArgs e) at DotNetNuke.Framework.PageBase.OnInit(EventArgs e) at System.Web.UI.Control.InitRecursive(Control namingContainer) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---

How do I restart the application?

 

thanks

Thank you both for the information. I restarted DNN. But, it did not. I also cleared cache, with no luck either. Luckily, this is a sandbox website for me. However, if you encountered this problem, what would you do next?

What book would you suggest for a beginner using DNN? The PDF manuals are good. But, the install process is a little confusing for me, because it is mixed up with box 3.x versions and 4.x versions. I'm ok, until I get to the web.config file part. It's hard for me to see exactly which part of the code strings to change. Maybe if the part that needed to be changed was in bold, red or blue, I could figure it out.

Is there some documentation  like this?

Thanks

James