Tuesday, 12 October 2010

NullReferenceExcepetion when viewing/editing an existing list item after the list instance has been deployed

Problem: When viewing or editing and item in a list, I receive an application error (NullReferenceException).  This happens when I redeploy a list, my list is defined using site columns, content type and the list definition is based on the content type.

My ULS logs contained the following information:
Failed to cache field with id
Unable to open Lookup list 'Lists/xxxList'.[Error was 0x8007....]
System.NullReferenceException: Object reference not set to an instance of an object.   at Microsoft.SharePoint.Publishing.FieldCache.TryGetValue

Initial Hypothesis:  ULS logs show me that a lookup list is not being found.  By examining the columns on the list instance I can see they are not being created correctly.  My initial thought was my xml was wrong, once it was reviewed and I found it to be correct I realised it was a caching issue.

Resolution:  Clear the Visual Studio Cache
  1. Right click on "Project" in Solution Explorer and click "Retract";
  2. Close Visual Studio 2010; and
  3. Open the "Project" in Visual Studio 2010 and "Deploy" the solution. 


Mohamed Hachem said...

if you have added any new field make sure that
it is not using a the guid of an existing field
this is how I solved it

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