[SOLVED] Index issues after upgrade from 5.x to 6.2

[Enis]

Hey,

I had the same problem and the solution for this problem is written in this post:

Failed to parse mapping for index

Get the current one using the index template API and update it. You can the push it back into the cluster using the same API. If you are using the default Logstash template, you can just upload the standard 6.0 template and overwrite the existing one.

I have deleted my saved logstash template and added the standard logstash template like mentioned.