Error on the Publishing Warnings gutter


Description

When "Publishing Warnings" are enabled in the Quick Actions bar in the Content Editor, an error icon would sometimes appear with the "PublishingWarnings gutter failed to render" message. This may happen if every version of the selected item in the current content language is hidden/unpublishable.
At the same time, the following exception would appear in log files:
Exception: System.NullReferenceException
Message: Object reference not set to an instance of an object.
Source: Sitecore.Kernel
at Sitecore.Shell.Applications.ContentEditor.Gutters.PublishingWarnings.GetTooltip(Item item)
at Sitecore.Shell.Applications.ContentEditor.Gutters.PublishingWarnings.GetIconDescriptor(Item item)
at Sitecore.Shell.Applications.ContentEditor.Gutters.GutterRenderer.Render(HtmlTextWriter output, Item item)

Solution

  1. Place the Sitecore.Support.318916.dll assembly in the /bin folder.
  2. Open Sitecore Client using the Desktop interface.
  3. Switch the database to "core".
  4. Open the Content Editor and navigate to the following item: 
    /sitecore/content/Applications/Content Editor/Gutters/Publishing Warnings
  5. Replace the contents of the Type field with the following value and save changes:
    Sitecore.Support.Shell.Applications.ContentEditor.Gutters.PublishingWarnings,Sitecore.Support.318916