@Sreejishnu what do you mean for running OpenUpgrade server? 

You need to see OpenUpgrade as a module, once you have cloned the OpenUpgrade with the same branch of the target version you need to initialize Odoo by giving the addons path where the scripts are contained. Within your main Odoo installation folder you should run a command similar to this:

python odoo-bin --upgrade-path=odoo_folder/OpenUpgrade/openupgrade_scripts -d db_to_migrate --update all --stop-after-init --load=base,web,openupgrade_framework

For further info you can read the official documentation at https://oca.github.io/OpenUpgrade/

Hi,

Please refer to the link below for the blog on database migration using OpenUpgrade for odoo v15.

 https://www.cybrosys.com/blog/how-to-upgrade-the-odoo-15-database-using-openupgrade

 https://www.cybrosys.com/blog/how-to-migrate-odoo-database-using-openupgrade

Hope it helps.