TSC: 404 for empty search result

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Katherine Watier Ong: The end result page that you get when you use their internal search is indexed - the long listing of results has not been indexed, and some of the end result pages have backlinks
  
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  Linda Ferguson: Google says they frown on search results being indexed because it generally causes a poor experience for users. They also say the algorithm is able to remove some internal search pages from sites...but better not to have them indexed in the first place. Noindex meta tags would be the way to go or add a noindex in the HTTP response header. support.google.com - Block search indexing with `noindex` - Search Console HelpBlock search indexing with `noindex` - Search Console Helpsupport.google.com
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  MEILI HONG: http://marketing909.blogspot.com/2017/10/the-role-of-translators-and-interpreters.html
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  Ankit Gupta: I use to have the same issue while working for a giant Cloud services provider of China (name need not be mentioned)
  
  1) Ideally, search result pages should be blocked from indexing. The reason is that such pages deliver poor user experience.
  
  2) However, at the same time, if the search result pages have already been indexed, it doesn`t make any sense to block them now.
  
  3) Place a canonical tag on all the dynamic search result pages pointing to one of your targeted pages (I would recommend the home page). This way all the content duplicity, links juice, meta tags will be handled. Moreover, with time, your homepage will start ranking for the queries for which the search result pages were ranking.
  
  4) For dynamic pages showing "no results" should have a 404 message (not 404 HTTP response) with few navigational links. So that the user has the ability to navigate further.
  
  Following all these, you will have a better user experience, and all link juice managed (external backlinks received to the search result pages).
  
  PS: Following the step 3, the number of indexed search result pages will reduce. So, the clients` expectations should be managed accordingly.