An ERP integration is rarely a purely technical project. The software usually works. What goes wrong almost always sits in the preparation: processes nobody mapped, integrations that surface too late, data that migrates dirty. Most mistakes are not accidents but predictable patterns. Below are the five we see most often in projects across the Benelux and DACH region, with the way we prevent them at SEMANU.
Timeline: where the five mistakes originate
Four out of five mistakes occur before the first line of code. This is the order in which they appear.
The five mistakes
Mistake 1. Choosing software without analysis
Many projects start at the demo. The slickest interface or the most familiar name wins, and only then do people check whether the processes fit. You end up integrating a system around workflows nobody wrote down first. The consequence: customization piles up, the standard gets bypassed and every exception becomes expensive change-work after signing.
How SEMANU handles this. Process analysis first. We map your current processes and their exceptions before implementation or development, so you choose on process fit rather than on the demo.
Mistake 2. Underestimating integrations with satellite systems
An ERP never stands alone: web shop, CRM, WMS, accounting, PIM, EDI, CAD. Each integration is a miniature project with its own data flow, owner and failure scenario. "We'll solve that later with a standard connector" is the classic that comes back to bite. Forgotten or deferred integrations are a top cause of budget overruns after go-live, because suddenly the ERP without that connection is worth only half.
How SEMANU handles this. An integration map: we name every connection, which data flows where and who owns it, so no satellite system gets "deferred". In a recent project we mapped 8 satellite systems before a single proposal was on the table.
Mistake 3. Letting the vendor define what "done" means
Without your own acceptance criteria you sign off on a demo that works instead of on your processes that work. The definition of "delivered" then comes from the party with an interest in delivering fast. The consequence shows up after go-live: scope discussions, change-work and no negotiating position because the contract is already signed.
How SEMANU handles this. We define what "done" means per phase, in your own words and measurable. You're not dependent on your vendor's definition, and everyone knows upfront what gets signed off against. Acceptance criteria are a fixed part of every Analysis.
Mistake 4. Ignoring data quality and data migration
Migrating fifteen years of data from the old system without cleaning is asking for trouble. Duplicate customers, half-filled article numbers, fields nobody understands anymore: the new ERP simply inherits the chaos of the old one. Garbage in is garbage out. And users who see wrong data on day one immediately lose trust in the system.
How SEMANU handles this. We treat data quality and migration as an explicit requirement with its own acceptance criteria, not as an afterthought just before go-live. Cleaning, mapping and testing with real data belong in the plan from day one.
Mistake 5. Underestimating change management and the real cost
Attention goes to the license price in the proposal, while that shows on average only one fifth of what the project will really cost over five years. Training, internal time and the production dip in the first months after go-live appear in no budget. The result: people fall back on the old way or on Excel, adoption stalls and the business case evaporates.
How SEMANU handles this. We compute a realistic 5-year TCO upfront, including training, internal time and operations. And with our Guidance we stay involved during and after implementation, so adoption isn't left to chance. Read more in our article on the real cost of an ERP.
The pattern
Four of these five mistakes are made before the first line of code, not after. They can therefore be made visible before you sign. That is the whole idea behind independent business analysis: first know what you need and only then sign. No vendor ties, no commissions, just the question of whether your investment delivers what it should.
Want this done for your ERP choice?
The SEMANU Analysis delivers exactly what's described above: a process map, integration map, acceptance criteria, a 5-year TCO projection and a specification document with which you can compare vendor quotes correctly. One-off investment from €4,400.
Frequently asked questions
What is the biggest mistake in an ERP integration?
Choosing software before you know your processes. Anyone selecting on the demo rather than on process fit pays for it later in customization and change-work. Map your processes and exceptions first, then choose.
Why do integrations with other systems go wrong so often?
Because they come into view too late. Every integration with web shop, CRM, WMS or accounting is a separate miniature project. An integration map before selection makes every data flow and owner explicit, so nothing is "for later".
How do you prevent an ERP project from overrunning its budget after go-live?
Make the hidden costs visible upfront. The proposal shows on average one fifth of the real cost over five years. Budget integrations, data migration, training and internal time separately and keep a buffer. That way the business case doesn't run empty after delivery.
Does SEMANU do the ERP implementation itself?
No, deliberately so. We don't sell software and take no commissions. We prepare your integration independently with process analysis, requirements, an integration map and acceptance criteria. After that we guide you during the implementation. That way the choice always stays yours.