In 28 years at ui42, we have gone through hundreds of development projects and migrations to new e-commerce platforms. And despite each project having its specifics, I perceive that very similar mistakes tend to repeat themselves.
I wrote this article for three reasons:
1. Repeating mistakes – many complications repeat and are predictable.
2. They cost money, time, and nerves – for clients and the agency, and in crisis moments, they can disrupt otherwise good relationships.
Know-how needs to be shared – maybe someone will return to this article in a year or two and remember a specific tip that makes their life easier.
1. Even technological projects rely on people
Migration to a new platform is not just about technology. It is always also about change management – and that is often underestimated. Often, the decision to change is made within a narrow group of managers, and other departments (warehouse, accounting, marketing, customer support) learn about it too late. The result? Internal processes suddenly don't work, people are unprepared, and frustration grows.
Practical tips:
- Involve all relevant departments already in the preparatory phase.
- Appoint a responsible person who lives the project.
- Use tools like Stakeholder mapping or RACI Matrix – clear roles = less chaos.
2. Marketing is not addressed in time
Most common technical-marketing missteps:
- Product IDs are not transferred to the datalayer → you lose campaign history.
- URLs are not correctly mapped → 404s and a drop in organic traffic.
- Feeds to comparators fail.
- Missing key scripts (GTM, Heureka Verified by Customers, NPS emails).
The problem is that programmers naturally do not perceive the web as a sales channel, more as "another project." From their perspective, these are "small tasks" that require a lot of communication, but they have a huge business impact. This is a challenge especially for project managers who are responsible for the project.
Practical tips:
1. Think about marketing already in the preparatory phase.
2. Involve the marketing team to define all data, feeds, and scripts.
3. Count on a temporary drop in organic traffic – if you prepare for it, it won't be stressful.
3. Design is not about creativity, but functionality
An e-shop is not a canvas for a creative act. It is a sales platform and must reflect user needs. This means psychology, behavioral data, UX standards, and research (I recommend Baymard or NNGroup).
Common mistakes:
- Forgetting about mobile first.
- Endless iterations → delays.
- Clients bypass the process and draw "on their own."
- Lack of UX testing with real users.
- Wrong approach: starting with a finished design, missing wireframes.
- Ignoring accessibility (European Accessibility Act).
uičkovský tip: Try to prototype quickly and cheaply – e.g., through Vercel v0 chat. The sooner you have a clickable prototype, the sooner you can test.
4. "We want everything at once" syndrome
The biggest project stopper: clients want everything at launch – new ERP, B2B and B2C, plus dozens of new functionalities. They often combine platform migration with ERP change. The result? Delays, bugs, frustration.
Tips for clients:
1. Do not change two key systems at once.
2. Divide the project into phases and set priorities.
3. Work with MVP and iterations.
4. Count on continuous development after launch.
Tips for suppliers:
1. Help the client create a realistic roadmap.
2. Recommend functionalities that have the greatest business impact.
3. Setting expectations correctly is often more important than technical skills.
5. Technical specification is a must-have
At ui42, we do not start without a technical specification. It is a detailed document that defines at least:
- Content structure, screens, functionalities.
- Integrations and process mapping.
- Business priorities and future change requests.
If the specification is missing, there is room for:
- "But we thought this would automatically be included..."
- Constantly increasing requirements → budget and time grow.
- Low sustainability for the future.
6. Testing is a process, not a one-time task
A simple rule applies: it's cheaper to change in Figma than in code. Therefore, test from the beginning.
Validation and testing options:
- Business validation of requirements.
- Wireframes and designs.
- Unit tests and E2E tests.
- Hypercare testing at launch.
- Post-release testing – it never ends.
Conclusion
Migration to a new e-commerce platform is always a complex project. However, if you avoid the above-mentioned mistakes, it can be manageable and relatively calm.
At ui42, we believe that quality preparation, open communication, and the involvement of all parties involved is the key to success.
If you are facing a similar decision and want to avoid blind alleys, we are happy to share our experiences with you.
