This error just started happening to one of our Custom Lists. Whenever you try to create a new item (or edit an existing), the following error occurs:
Server Error in '/' Application.
--------------------------------------------------------------------------------
Value cannot be null.
Parameter name: value
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.ArgumentNullException: Value cannot be null.
Parameter name: value
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:
[ArgumentNullException: Value cannot be null.
Parameter name: value]
System.Collections.CollectionBase.OnValidate(Object value) +61
Telerik.WebControls.RadEditorUtils.ToolbarCollection.OnValidate(Object value) +17
System.Collections.CollectionBase.System.Collections.IList.Remove(Object value) +54
Telerik.WebControls.RadEditorUtils.ToolbarCollection.Remove(Toolbar toolbar) +29
Telerik.SharePoint.ListFieldEditor.RadHtmlListField.OnLoad(EventArgs e) +615
System.Web.UI.Control.LoadRecursive() +101
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2588
TOther lists (where the RADEditor) is used work fine.
Server Error in '/' Application.
--------------------------------------------------------------------------------
Value cannot be null.
Parameter name: value
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.ArgumentNullException: Value cannot be null.
Parameter name: value
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:
[ArgumentNullException: Value cannot be null.
Parameter name: value]
System.Collections.CollectionBase.OnValidate(Object value) +61
Telerik.WebControls.RadEditorUtils.ToolbarCollection.OnValidate(Object value) +17
System.Collections.CollectionBase.System.Collections.IList.Remove(Object value) +54
Telerik.WebControls.RadEditorUtils.ToolbarCollection.Remove(Toolbar toolbar) +29
Telerik.SharePoint.ListFieldEditor.RadHtmlListField.OnLoad(EventArgs e) +615
System.Web.UI.Control.LoadRecursive() +101
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Control.LoadRecursive() +211
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2588
TOther lists (where the RADEditor) is used work fine.