Hi Tom and welcome to our :)

Have you changed anything in the installation? Or installed a new package for instance?

What happens if you browse to the forum and add ?umbdebugshowtrace=1 - does the trace log give any further clues?

/Jan

Hi Jan,

thank you for your reply!

I add some macros to nforum, but everything was OK for a few days and then the error occured :(

Debug didn't tell me anything, or at least I don't see anything weird. Maybe you will (I'm not so experienced):

* please note that KubaCestopisy.ascx.cs is in fact copy of ForumActiveTopics.ascx.cs with just a slight change (I've used it for some time without any problem).

Don't know if pasting of the whole trace information will help to determine the problem, I think it have to do something with our.umbraco.org/.../20901-umbraco-to-linq-null-object-issue-plus-solution-(not-really) but I don't know how to solve it at all :(

To clarify the situation - I'm not able to browse nforum. Every page that has any macro from nforum doesn't work - Null object cannot be converted to a value type error occures every time. But I can browse any other page, therefore I suspect nforum for having some problem, but I don't know where it could be...

In fact I can't even click root node (Content) in Content section of Umbraco administration (the same error appears, probably because there is some nforum panel), but I can browse nforum content (all nodes of nforum) in administration (and that's weird).

Root node in Content section of Umbraco administration throws above mentioned error, but the trace seems little different:

[InvalidCastException: Null object cannot be converted to a value type.]
 System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider) +12819958
 System.Convert.ChangeType(Object value, Type conversionType) +133
 umbraco.Linq.Core.Node.NodeDataProvider.LoadFromXml(XElement xml, T node) +1644
 umbraco.Linq.Core.Node.NodeTree`1.GetEnumerator() +527
 System.Linq.WhereEnumerableIterator`1.MoveNext() +107
 System.Linq.<TakeIterator>d__3a`1.MoveNext() +376
 System.Web.UI.WebControls.GridView.CreateChildControls(IEnumerable dataSource, Boolean dataBinding) +1819
 System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data) +94
 System.Web.UI.WebControls.GridView.PerformDataBinding(IEnumerable data) +18
 System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data) +182
 System.Web.UI.WebControls.DataBoundControl.PerformSelect() +274
 nForum.usercontrols.nForum.dashboard.ForumMainDashboard.GetBadPosts() in D:\Umbraco\nForum\usercontrols\nForum\dashboard\ForumMainDashboard.ascx.cs:27
 nForum.usercontrols.nForum.dashboard.ForumMainDashboard.Page_Load(Object sender, EventArgs e) in D:\Umbraco\nForum\usercontrols\nForum\dashboard\ForumMainDashboard.ascx.cs:11
 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +25
 System.Web.UI.Control.LoadRecursive() +71
 System.Web.UI.Control.LoadRecursive() +190
 System.Web.UI.Control.LoadRecursive() +190
 System.Web.UI.Control.LoadRecursive() +190
 System.Web.UI.Control.LoadRecursive() +190
 System.Web.UI.Control.LoadRecursive() +190
 System.Web.UI.Control.LoadRecursive() +190
 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3064

Error leads to ForumMainDashboard.ascx.cs where nforum loads and display bad posts (spam). In my case it throws mentioned error.

Nobody knows how to solve this? :-(

Hi Tom

Coming to think of it this may be due to some changes in the backoffice perhaps?

Has there been any modifications done on document types in Umbraco? Have some pickers been used, which referene nodes that no longer exists etc.?

/Jan

Hi Jan,

yes, there have been some changes in document types etc, but I double check it now to be sure, it doesn't refere to nonexisting nodes.

Weird is, that everything worked for few days and then suddenly error appeared.

Isn't it possible that there is some problem with any kind of cache or xml file that nforum creates? It seems to me like some connection between nodes is broken. So maybe "reseting" nforum to reload all xml files and nodes would help, but I dunno how to do that and if it is even possible... Simple republishing etc don't work.

Tom

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