I encountered an exception when I tried to create form on contour, by right clicking the Forms->Create. Also, it doesn't allow me to delete form.

I recently upgraded both Umbraco and Contour to below:

Umbraco v 4.11.5 (Assembly version: 1.0.4807.33359)

Contour version 3.0.9

Detailed exception when trying creat a from using context menu is below:

Server Error in '/' Application.
The create dialog for "forms" does not match anything defined in the "~/umbraco/config/create/UI.xml". This could mean an incorrectly installed package or a corrupt UI file
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.ArgumentException: The create dialog for "forms" does not match anything defined in the "~/umbraco/config/create/UI.xml". This could mean an incorrectly installed package or a corrupt UI file

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:

[ArgumentException: The create dialog for "forms" does not match anything defined in the "~/umbraco/config/create/UI.xml". This could mean an incorrectly installed package or a corrupt UI file]
   umbraco.cms.presentation.Create.Page_Load(Object sender, EventArgs e) +609
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
   System.Web.UI.Control.OnLoad(EventArgs e) +92
   umbraco.BasePages.BasePage.OnLoad(EventArgs e) +14
   System.Web.UI.Control.LoadRecursive() +54
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +772

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.17929

 Exception when trying to delete a form:

"NetworkError: 500 Internal Server Error - http://uk.umbraco.local/umbraco/webservices/legacyAjaxCalls.asmx/Delete"

Response:

{"Message":"Object reference not set to an instance of an object.","StackTrace":"   at umbraco.presentation.create.dialogHandler_temp.Delete(String NodeType, Int32 NodeId, String Text)\r\n   at umbraco.presentation.webservices.legacyAjaxCalls.Delete(String nodeId, String alias, String nodeType)","ExceptionType":"System.NullReferenceException"}