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Odoo migration: from a legacy ERP or from one version to the next
A migration is not an installation project, it is a switchover project.
An Odoo migration comes in two forms: the ERP migration (replacing a system in production with Odoo) and the Odoo version upgrade (moving your database from one version to the next). In both cases the risk is never technical: it lies in the data migration, in the buy-in of the teams and in the choice of what you leave behind along the way.
Our fastest migration was delivered in two months, without a single day of business downtime. What makes that possible is not execution speed, it is discipline on the scope and on the cut-off date.
How long does an Odoo migration take?
Short answer: an ERP migration to Odoo runs in five phases: audit of the existing system, arbitration of scope and custom work, data migration, user acceptance testing and switchover on a cut-off date. Allow two to nine months depending on the size and condition of the data.
That project involved an industrial manufacturing company of ten people, with seven modules deployed. An upgrade between two Odoo versions is a shorter undertaking, but it follows the same logic: audit, test on a copy, then switch over.
Our migrations in figures
5
phases
2-9
months: typical duration of a migration
2
months: fastest migration
0
days of business downtime
What makes a migration fail
Four causes, all avoidable, none technical.
Reproducing everything as-is
Recreating in Odoo the workarounds accumulated in the old system means importing the debt. Every specific feature is questioned again: is it the business, or is it the old tool?
Underestimating data migration
Duplicate partners, obsolete products, wrong theoretical stock: cleansing comes before migration. It is the most underestimated item in every project.
Migrating ten years of history
Three financial years are almost always enough. Beyond that, the cost far exceeds the real use that will be made of it.
Switching over without acceptance testing
If users haven't replayed their own processes on their own data, the switchover is paid for in fixes over six months.
The five phases of an ERP migration to Odoo
1
Audit of the existing system
Inventory of processes, interfaces, custom work and data quality. Written deliverable, including what we recommend not migrating. It starts with the free on-site situation audit.
2
Scope arbitration
What goes into batch 1, what waits, what disappears. Decided with you, written down and binding during the project.
3
Data migration
Partners, products, stock, outstanding balances and an arbitrated history. Several test iterations before the final migration.
4
User acceptance testing
Your teams validate on their real data. Nothing goes live without formal sign-off.
5
Switchover on a cut-off date
Usually over a weekend, with a rollback plan. Reinforced presence during the first days of operation.
Odoo version upgrade: moving from Odoo 16, 17 or 18 to Odoo 19 or 20
Odoo 20 is available. The vendor supports the last three major versions: Odoo 17 has no longer been supported since the release of Odoo 20 and versions 16 and 15 no longer receive security fixes. Planning the upgrade early protects your ERP and simplifies every future migration.
Hosting changes the timetable. On Odoo.sh, the platform requires a version supported by the vendor: the migration is therefore unavoidable and is scheduled in advance. On a dedicated server, on-premise or in a private cloud, your version keeps running, but without the vendor's security fixes: the upgrade is then planned at your own pace, with a target date and a test database.
- Audit of custom developments. We list every custom module and decide whether it is ported, simplified or replaced by a function that has become standard.
- Test database. The upgrade is first played out on a copy of your database, where your users check their processes with no risk to production.
- Switchover. After acceptance testing, production switches over on an agreed date, with a rollback plan.
- Follow-up. During the first days, we give priority to the discrepancies reported by the teams.
Porting custom modules is costed within the project, which is why we limit custom work to the strict minimum. To spot what changes between two versions, see our cluster on Odoo versions, including what's new in Odoo 20 module by module.
Frequently asked questions about Odoo migration
Yes, as long as the data can be exported. The difficulty comes from its quality more than from the source tool. We audit the existing system before promising a schedule.
No. The switchover is prepared for a cut-off date, usually a weekend, with a rollback plan. Our fastest customer case ran with no interruption to business.
Three financial years are almost always enough. The rest can remain viewable in the old system in read-only mode.
They must be ported to the new version. We audit them first: some become unnecessary because the standard has evolved.
As soon as possible for Odoo 16 and 15, which no longer receive security fixes. For Odoo 17, vendor support has ended since the release of Odoo 20. On Odoo.sh the platform requires a supported version; on a dedicated server the database remains usable while the upgrade is prepared.
Straight to the target version. The vendor's upgrade service converts the standard database from an old version to the chosen one in a single operation; we then port the custom modules and replay your processes on a test database before the switchover.
The cost depends on the volume of data to migrate, the number of custom modules to port and the number of interfaces. The licence stays the same: €35.90 per user per month for the first year with Odoo's Custom plan, then €44.90. We quote the service after the audit of the existing system, never before.
Consulting and scoping before you migrate
An ERP migration is first of all an organisational decision. Our organisation consulting practice helps you frame it: a free on-site situation audit, the choice of what gets simplified along the way, the requirements document and project steering if your team wants it. Still unsure about which tool to choose? Our comparisons pit Odoo against Sage and Odoo against Cegid, with no bias about what your current system does well.
Let's talk about your Odoo migration
Thirty minutes to assess your existing system, the volume of data to migrate and the realistic path.