When a business upgrades Odoo, its custom modules have to be carried to the new version. This piece is about migrating an Odoo module across versions.
What migrating a module means
Migrating an Odoo module across versions is carrying a custom module from one Odoo version to a newer one: making the module, built for the old version, genuinely work on the new version. When a business upgrades Odoo, each of its custom modules has to be migrated this way, so the custom functionality the business depends on genuinely works on the version it is upgrading to.
Why a module has to be migrated, not just moved
A module has to be genuinely migrated, not just moved, because a new Odoo version can differ from the old in ways the module depends on. The module was built against the old version, and a new version can change things the module's code relies on. So a module carried unchanged to a new version may not genuinely work; it may need adjustment, sometimes substantial, to work on the new version. Migrating the module is making those adjustments, so the module, on the new version, genuinely works as it did.
How migrating a module is approached
Migrating a module is approached, sensibly, as a deliberate piece of work. It begins with understanding what the module needs, which is what auditing the custom code provides: the audit reveals what in the module will need adjustment for the new version. Then the module is genuinely migrated: the adjustments are made, so the module's code works on the new version. And the migrated module is genuinely tested, so it is confirmed that the module, migrated, genuinely works on the new version, rather than that being assumed. Migrating a module is the deliberate work of understanding what it needs, adjusting it, and confirming it works.
How clean development eases module migration
An honest point that matters. How hard a module is to migrate across versions depends heavily on how the module was built. A module built cleanly, the Odoo way, extending Odoo cleanly through inheritance rather than fighting the framework, is far easier to migrate: it adapts to a new version far more readily. A module built carelessly, against the grain of the framework, is far harder to migrate. So the ease of migrating a module is, in large part, decided long before the upgrade, by how cleanly the module was built. This is one of the strongest reasons to build modules cleanly, the Odoo way, in the first place: it is what makes them migratable when the time comes.
The takeaway
Migrating an Odoo module across versions is carrying a custom module to a new Odoo version, making it genuinely work there. A module has to be genuinely migrated, not just moved, because a new version can change things the module depends on, so it may need adjustment. Migrating a module is the deliberate work of understanding what it needs, through the audit, adjusting it, and testing that it works. How hard the migration is depends heavily on how cleanly the module was built, which is a strong reason to build modules cleanly, the Odoo way, from the start. For how we approach Odoo, see our ERP practice.