can we upgrade jira 3.6.3 to the latest version, If it is possible could you please share the document?

[Nic Brough -Adaptavist-]

Yes.  Please read https://confluence.atlassian.com/display/JIRA/Upgrading+JIRA to get started with.  

You WILL need to step through more than one version - I'd suggest 3.6 -> 3.11, then 4.4 then 5.2 then 6.3, but you must test that for your own system and adjust it if you need to

[Rodrigo Girardi Adami]

Hi Siva,

I recommend to step in some major versions before reaching the latest version like going to 4, 5 and then 6.4 version for safety reasons. Also, always perform a backup before any upgrade or change and between upgrades to create some check points.

Cheers,

Rodrigo