Your data is the implementation. Everything else is configuration.
Ask any experienced ERP consultant where implementations most commonly go wrong, and the answer is rarely the software. It's not the project plan, the vendor, or even the change management program. It's the data. Specifically: the decision — made early, often casually — to migrate existing data into a new system without first asking whether that data is worth migrating at all.
The consequences compound quietly. Duplicate customer records proliferate. Inventory valuations carry forward assumptions that no longer reflect reality. Chart of accounts structures built for a business that no longer exists get mapped into a platform that was supposed to fix all of that. By go-live, the shiny new ERP is running on the same dirty foundation the old one was. Six months later, leadership wonders why nothing actually changed.
The audit phase almost nobody does properly
A serious data migration begins not with extraction but with interrogation. Before a single record is touched, the right questions are: What data do we actually need in the new system to run the business on day one? What do we need for historical reference but not active use? And what can we retire entirely? These are business questions, not technical ones, and they need business owners in the room to answer them — not just IT.
This audit typically surfaces more than expected. Vendor records that haven't been touched in years. Product catalog entries for items that were discontinued before most of the current team was hired. Customer accounts that belong to contacts who no longer exist. Every one of these represents a decision: migrate it, archive it, or cut it. The instinct is to keep everything. The discipline is to keep only what earns its place.
Mapping is where strategy becomes structure
Once the audit is complete, the migration mapping process translates the current data model into the new system's structure. This is where technical complexity meets business logic — and where the two must be reconciled deliberately rather than assumed to align.
Common failure points here include:
- Account code mapping done by accountants without developer input, resulting in structures the system can't report on correctly.
- Product attribute mapping done by IT without operations input, resulting in a catalog that looks correct but doesn't support manufacturing BOMs or pricing logic as intended.
- Open transaction migration without cutover alignment, where AR and AP balances move without agreement on the cutover date, creating reconciliation nightmares that take weeks to unwind.
Every one of these is predictable. Every one of them is preventable with a mapping process that involves the right people at the right time.
Validation is not a QA step — it's a business sign-off
A common mistake is treating data validation as a technical checklist: row counts match, foreign keys resolve, no null values where nulls aren't permitted. These checks matter. But they are not the same as business validation, which asks a different question entirely: does this data accurately represent the state of our business as of the cutover date?
Business validation means a warehouse manager confirms that the inventory quantities in the new system match what's physically on the shelves. It means a finance lead reconciles the opening balances against the last close. It means an operations lead spot-checks a sample of active work orders and confirms the data looks right. This takes time. It sometimes surfaces problems that require re-migration. And it is non-negotiable, because the alternative is discovering those problems after go-live — when the cost of fixing them is orders of magnitude higher.
What a good migration strategy actually looks like
The migrations we're most proud of share a few characteristics. They started earlier than the client expected — typically in the first weeks of the engagement, not as a late-stage activity. They involved business stakeholders in decisions that looked like technical ones, because those decisions have business consequences. They included at least one mock migration before the real one, so surprises surfaced in a controlled environment rather than on cutover weekend. And they treated the cutover plan as a shared document that every team lead had reviewed and signed off on, not a project manager's artifact.
None of this is exotic. It's discipline applied consistently to a phase of the project that too many firms treat as a box to check rather than a foundation to build.
Your new ERP will run as well as the data you put into it. That means the migration strategy is not a migration question. It's an implementation question. Treat it accordingly from day one.