I am having a similar issue. I just installed nforum, following the video instructions at http://vimeo.com/34945384. The login and registration pages load properly, but when I try to access forum.aspx I get the following error:

Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
   nForum.BusinessLogic.Data.ForumFactory.ReturnAllCategories(Boolean useNodeFactory) +143
   nForum.usercontrols.nForum.ForumMainList.CreateMainForumList() +97
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +24
   System.Web.UI.Control.LoadRecursive() +70
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3047

Hi

Adding the catagory fixed my problem.Be sure to add Forum Category as a child node to Form Master.

Form Master

|

| ---------------------- Forum Category

Cheers

If you are using Umbraco v4.8 then you need to use the latest version of nforum (1.6) which was released today. 

Also when you install, create a category and make sure you fill in the settings tab on the category (Karma amounts allowed etc...)

Hi Lee,

I get this error:

Error creating control (usercontrols/nForum/ForumMainList.ascx).
Maybe file doesn't exists or the usercontrol has a cache directive, which is not allowed! See the tracestack for more information!

Trace says:

I uninstalled v.1.5 and reinstalled v.1.6 and it removed the Examine.dll and when I put it back from v.1.5. then it gave me this message:

Configuration Error

Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. 

Parser Error Message: Could not load file or assembly 'UmbracoExamine' or one of its dependencies. The system cannot find the file specified.

Source Error: 

Line 12:  <providers>
Line 13:        <add name="nForumEntryIndexer" 
Line 14: type="UmbracoExamine.UmbracoContentIndexer, UmbracoExamine" Line 15:          dataService="UmbracoExamine.DataServices.UmbracoDataService, UmbracoExamine" 
Line 16:            indexSet="nForumEntrySet" 

Then I put Examine.dll and UmbracoExamine.dll from the CMS but no luck.

And finally I put in Examine.dll and UmbracoExamine.dll from the nForum v.1.6 and then it gave me a lucene error and then I added the Lucene.Net.dll from v.1.5 and then this happened:

Now I have uninstalled v.1.6. and reinstalled v.1.5. and installed v.1.6 ontop and the result is.....IT WORKED!!!!!!

Thank you.

However, now accessing the top category gives this error:

The examinesetting config is malformed, best best is top grab a new umbraco 4.8 copy, get it up and running with SQLCE quickly, install nforum 1.6 then copy the examine configs to your existing project.

Okay, but should I then install 1.5. on this new installation or just 1.6?

For some reason it still says:

[NullReferenceException: Object reference not set to an instance of an object.]
   nForum.BusinessLogic.Models.Forum.MapForumNodeToModel(INode forumRoot) +317
   nForum.BusinessLogic.Helpers.MainForumSettings() +166
   nForum.usercontrols.nForum.ForumTopics.GetTopicsFromCategory() +996
   nForum.usercontrols.nForum.ForumTopics.Page_Load(Object sender, EventArgs e) +62
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +24
   System.Web.UI.Control.LoadRecursive() +70
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3063

I have the forum in the root node just below Content

Uninstalled and removed ANY trace of nForum.... and you know what... it worked like a charm :)

Cause I reinstalled and voila!

Hi All 

Upgraded to Umbraco 4.9 and nForum 1.6 and received the same problem again.  I had to amend Examine config files.

Later

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