Hi,

Yes, it's possible and free with a valid Enterprise subscription.

Important: Custom Tables & Fields :

Odoo's upgrade service handles standard module data automatically. For custom modules, their source code must be up-to-date with the target version before the upgrade can be performed Odoo — which you've already done. Custom table data (rows) generally carries over, but custom fields on standard models need your migrated module to define them so the upgrade script maps them correctly. Test this thoroughly.

Steps :

    Take a full backup — pg_dump + filestore (your 205GB dump). At 205GB expect upload/processing time to be significant.

    Go to upgrade.odoo.com → select "On-Premise" → fill the form with your source version (14), target (18), and subscription key.

    Submit as TEST first — not production. Once you get the migrated database, test it in your staging environment. Any issues will be fixed here, and this process may take a few iterations. Cybrosys Technologies

    Validate — test all business workflows, custom module behavior, and data integrity on staging.

    Submit production — once testing passes, repeat the same process for the live DB.