Workbox RSS throws exception after upgrading to 8.1 Update 3

Question

After upgrading my site from 7.5 to 8.1 Update 3 and when trying to open Sitecore workbox and clicking on the RSS feeds icon on any workflow; the following error appears:

4568 2016:10:21 07:06:59 ERROR Application error.
    Exception: System.InvalidOperationException
    Message: workflow
    Source: Sitecore.Kernel
       at Sitecore.Shell.Feeds.FeedFormatter.WorkflowEventTitleAndCaption(Item item, WorkflowEvent workflowEvent)
       at Sitecore.Shell.Feeds.FeedTypes.Workflow.BuildSyndicationItem(Item item, WorkflowEvent workflowEvent)
       at Sitecore.Shell.Feeds.FeedTypes.Workflow.GetSyndicationItems()
       at Sitecore.Shell.Feeds.FeedTypes.ClientFeed.Render()
       at Sitecore.Shell.Feeds.FeedRequestHandler.DoProcessRequest(HttpContext context)
       at Sitecore.Shell.Feeds.FeedRequestHandler.ProcessRequest(HttpContext context)
       at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
       at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Any ideas of what is the cause of this error?

Answer 1

While building the RSS workbox, Sitecore uses direct SQL call to the database to get all the items in particular workflow state.

Then for every item it tries to get workflow state and then it tries to get workflow from that state.

It looks like in your database you have corrupted workflow state information - maybe some workflow states are not migrated properly or some workflows?

I would start with removing broken links and see where it goes.