Hello Akhil,

If you are covered by the Odoo Enterprise contract, you will be automatically provided the upgrade/migration service. This is the official and best way to upgrade your database to  newer version.

You pay extra only if you wish Odoo to migrate custom modules too. But since you have already migrated custom modules yourself, you just need to add them in your addons-path allow them to load with your already upgraded database.

Detailed steps of the official Odoo Upgrade process is explained at https://upgrade.odoo.com/database/upload , where you can also upload your database.

You might also find this post (https://www.odoo.com/forum/help-1/question/how-to-upgrade-to-v7-with-opw-contract-2580) helpful which explains a migration for v7.0 (the overall process is the same for upgrades to v8.0, v9.0, etc.)

Hi Akhil, 

I have also gone many times this situation when i need to migrate data from odoo version 8 to odoo version 9, in such case the way i preferred is - 

1) Make that module compatible to the later version of odoo.

2) For data migration, do manually(LOL) or use some Posgresql commands(Not preferred as it not following odoo ORM methods), The best way among all is -- Make 1 script based on xmlrpc which interact with your previous odoo database, and populate same data to the later one.

For me, it is working perfectly till now.

Feel free to share any other way, if any :D 

Hello Akhil

First check functionality odoo 8 and also check any changes  depends module in odoo9