Upgrading to Magento 2
Unlike minor Magento upgrades such as upgrading from Magento 184.108.40.206 to 220.127.116.11, migrating from
Magento 1.x to Magento 2.x is a far more involved process. Custom themes and functionality will need to be migrated over and integrated
with the new codebase, which differs substantially from Magento 1.
This sounds like a lot of work!
There is no way of getting around it. It is a big job and whilst Magento do provide a couple of migration tools to help migrate existing custom and
product data, migrating your themes and functionality is very much a manual process.
The good thing is that this is the perfect opportunity to take a fresh look at you website, understand which areas are being used as intended,
clean out any unused functionality that is no longer required, and give the design a once-over.