We're using DNN 4.6.2 with DNN forum 4.4.3

After using the Thread Split feature, Users have noticed a failure in their 'My Post'  When they click on the Split Thread  they receive A critical error has occurred. Value cannot be null. Parameter name: value

with the following in the event view:

DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: e3012f7a-b697-42b1-a2af-777da69e7d05
InnerException: Value cannot be null. Parameter name: value
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Web.Caching.CacheEntry..ctor
StackTrace:
Message: DotNetNuke.Services.Exceptions.PageLoadException: Value cannot be null. Parameter name: value ---> System.ArgumentNullException: Value cannot be null. Parameter name: value at System.Web.Caching.CacheEntry..ctor(String key, Object value, CacheDependency dependency, CacheItemRemovedCallback onRemovedHandler, DateTime utcAbsoluteExpiration, TimeSpan slidingExpiration, CacheItemPriority priority, Boolean isPublic) at System.Web.Caching.CacheInternal.DoInsert(Boolean isPublic, String key, Object value, CacheDependency dependencies, DateTime utcAbsoluteExpiration, TimeSpan slidingExpiration, CacheItemPriority priority, CacheItemRemovedCallback onRemoveCallback, Boolean replace) at System.Web.Caching.Cache.Insert(String key, Object value, CacheDependency dependencies) at DotNetNuke.Services.Cache.FileBasedCachingProvider.FBCachingProvider.Insert(String CacheKey, Object objObject, Boolean PersistAppRestart) at DotNetNuke.Common.Utilities.DataCache.SetCache(String CacheKey, Object objObject) at DotNetNuke.Modules.Forum.ThreadInfo.GetThreadInfo(Int32 ThreadID) at DotNetNuke.Modules.Forum.Posts..ctor(DNNForum forum) at DotNetNuke.Modules.Forum.DNNForum.CreateObject() at DotNetNuke.Modules.Forum.DNNForum.CreateChildControls() at System.Web.UI.Control.EnsureChildControls() at DotNetNuke.Modules.Forum.ForumBaseControl.EnsureChildControls() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---
Source:
Server Name: SERVERLANDO

On closer inspection the Thread Split has failed to 'split' the thread.  It has trimmed the thread by removing the non-select posts. 

Does DNN log this event?  Is there any recovery method(s)?

Any suggestions would be appreciated.

I have just split a thread and all but the selected posts appear to have been deleted, is there a way of recovering these posts as my forum page is now afflicted with the same error that often hits these forums and screws the display

In my case, it appears that the problem was because the LastPostedPostID in the thread record in forum_threads after the split, was still showing the pre-split LastPostedPostID value.  Once that was corrected, the thread showed up in the forum, and is viewable again.