Hello all,

We had migrated our database from mySql to SQL server 2012 fro umbraco v4.6.2 site.

Now, the problem is while login at admin side I got an error like :

"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:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.] umbraco.BusinessLogic.<>cDisplayClass14.12(XDocument doc) +678 umbraco.BusinessLogic.ApplicationTree.LoadXml(Action`1 callback, Boolean saveAfterCallback) +149 umbraco.BusinessLogic.ApplicationTree.EnsureCache() +204 umbraco.BusinessLogic.ApplicationTree.get_AppTrees() +8 umbraco.BusinessLogic.ApplicationTree.getAll() +11 umbraco.cms.presentation.Trees.TreeDefinitionCollection.RegisterTrees() +68 umbraco.cms.presentation.Trees.TreeDefinitionCollection..ctor() +20 umbraco.cms.presentation.Trees.TreeDefinitionCollection..cctor() +30

[TypeInitializationException: The type initializer for 'umbraco.cms.presentation.Trees.TreeDefinitionCollection' threw an exception.] umbraco.cms.presentation.Trees.TreeDefinitionCollection.get_Instance() +14 umbraco.controls.Tree.TreeControl.Initialize() +174 umbraco.controls.Tree.TreeControl.OnPreRender(EventArgs e) +47 System.Web.UI.Control.PreRenderRecursiveInternal() +83 System.Web.UI.Control.PreRenderRecursiveInternal() +155 System.Web.UI.Control.PreRenderRecursiveInternal() +155 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +974

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34249 "

Any help would be greatly appreciated.

Thanks, Naresh