K2 5.3 supports SQL 2014, 2016, 2017 and SQL Azure.  

Here is the official documentation:

https://help.k2.com/k2compatibilitysupportmatrix

Hi MitchellR,

You may refer to the below link for the compatibility matrix

https://help.k2.com/k2compatibilitysupportmatrix

Should you feel that this post is of use and or an accurate solution to the raised question, I kindly encourage you to mark it as such
using the 'Mark as Solution', 'Kudo' andor ‘Me Too’ options.

Cheers,
Kate

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