A Collection of Epic Fails Due to Lack of non-WWW Redirects

Sometimes people commit mistakes in web redirection concerning the use or not of www. as a subdomain of the main site hosted on a given domain. Most errors split in two types:

• Serving the same content on two base URLs, due to hosting the same content in www.chosendomain.com and chosendomain.com. 
• The web server is not running on the base domain, only on www subdomain, which results in a page not available type error that confuses people that forget to type the www. part of the URL - this is a loss of potential customers, and hence the "Epic Fail" title for this post.

Both errors are easy to fix, and you have alternate ways to fix the first one. If you're using <link rel="canonical"></link> to specify which page should be indexed, Google will index it only with the hostname you provided and all the pagerank will go towards the URL you choose for your website.
To do a simple redirect, check your tutorial at this link: URL redirection www or non-www.

Errors of not serving nor redirecting www. base domain

http://svdvyver.com/
http://worten.pt

SSL errors due to lack of non-www redirection

This is a particularly interesting error, since I hadn't met it yet. I was finding it strange that this website had an invalid domain and further research unveiled that the certificate authority issued it only for www.uzo.pt and not uzo.pt, which is expected. A simple redirect fiex

https://uzo.pt/pt/adiro-ja/manter-numero/optimus/pagina.uzo