When you've got non-HTML pages on your web site, for example PDFs or spreadsheets, you won’t have the ability to carry out hreflang while in the in the HTML as it doesn’t exist.  Ensure your XML sitemap only incorporates canonical pages. This allows serps explore the correct URLs to index. https://minibookmarks.com/story18760558/an-unbiased-view-of-hreflang-canonical