Migration Aerospike ver.3.15 to ver.6

I want to know about the documents or side effects needed to migration aerospike version 3.15 to 6.2

You can check the special upgrades docs: Special Upgrades | Aerospike Documentation. But hard to have an exhaustive list of potential side effects as some features may have been deprecated, config changed, etc… If you have an Enterprise License, Aerospike may be able to provide some tailored advice or help through a formal engagement.

Otherwise, you could take a back and restore and run some tests on the 6.2 version.