Canonical points at a broken URL
What it means
The canonical tag names a URL that does not return 200. A canonical pointing at a 404 or a redirect tells search engines to index something that is not there, which usually means neither URL gets indexed.
How to fix it
Point the canonical at the final, working URL: the one that returns 200 directly, with no redirect. Check the scheme, the host and the trailing slash: a canonical to the http:// version of an https:// page is the most common form of this mistake.
Finding it in CrawlStat
After a crawl, open Issues and pick Canonical points at a broken URL. Click Show all in Pages to filter the Pages table to the affected pages, or Export affected to hand the list to whoever owns the fix. Audit ID: canonical_non_200.