Hi Maaz,

When upgrading custom modules—say from Odoo 18 to 19—there are two common approaches:

1. Install the existing module in Odoo 19 and fix issues progressively.

You begin by updating the version in __manifest__.py, and then resolve compatibility problems as they show up during testing. This is practical when the module is large or deeply customized.

2. Rebuild the module for Odoo 19.

Here you re-implement the logic and functionality from scratch while following Odoo 19 standards and APIs. This approach is ideal for smaller modules or those that would benefit from cleaner, modern code.

In general, rewriting works best for small modules, while incremental fixing is more efficient for larger codebases.