how to Upgrade Grails from Grails 2.4.4 to Grails 3.3.6?

I need to upgrade my grails application from 2.4.4 to 3.3.6. is there any smart way to do it or any kind of help if you can share your experience.

Always follow the official upgrade guides.

There are upgrade guides from 2.x -> 3.2 and then from 3.2 -> 3.3

• 2.x -> 3.2: http://docs.grails.org/3.2.x/guide/upgrading.html#upgrading2x
• 3.2 -> 3.3: http://docs.grails.org/3.3.0/guide/upgrading.html

So you need to perform upgrade in 2 separate steps.