The canonical tag indicates which page version Google should index, so there should be no reason for a broken canonical that references a 4xx or 5xx status URL. This issue can result in either the wrong page version being indexed, or no pages being indexed for the keyword you want to rank for.

Under the "documents" list in the report below, you can see which pages contain a broken canonical. The canonical targets list shows you the broken link the canonical tag is linking to. Download the report, log in to your content management system, and work through the documents one by one to change the canonical tag, or pass the list on to your developers.Learn more in our wiki and magazine