Change record status: 
Introduced in branch: 

In Drupal 8 Entity validation is moved to a separate Entity validation API and so decoupled from form validation. Having entity validation decoupled from forms allows validation entities independently from form submissions, e.g. when changed via RESTful web service. This new validation API has been implemented based upon Symfony validator.

Current status:
[WIP] - the new validation API is in place and fully functional, but it is not used for validating entity forms yet. Check #1696648: [META] Untie content entity validation from form validation for further conversion details.

Read the validation API documentation provided here.

Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
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Module developer documentation: 
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Examples project: 
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Coder Review: 
Not done
Coder Upgrade: 
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Other updates done