An MVP exists to learn fast with little. That’s why it’s tempting to leave design for later: “first make it work, then make it pretty.” The problem is that user experience isn’t the paint job. It’s the structure. And structure is the most expensive thing to change once there’s code, data and users on top of it.

These are the mistakes that, in our experience designing and building products, cost the most to fix later. None of them is solved with a color palette.

1. Designing screens instead of flows

The most common mistake is starting with the home screen, then the profile, then settings, as if the product were a catalog of views. Users don’t use screens: they complete tasks. Sign up, create their first project, invite someone, pay.

When you design by screens, each one can be fine while the full journey is broken. The user ends up in a dead end, or needs six steps for something that should take two. Before opening a design tool, write down the three or four flows your MVP must solve end to end. Everything else is secondary.

2. Ignoring the empty state

We design with sample data: full tables, charts with nice curves, lists with ten items. But the first time a user opens your product, they have nothing. They see a blank screen and don’t know what to do.

The empty state is, literally, your product’s first impression. It needs to explain what goes there, why it matters and what the first step is. A good empty state is the difference between a user who stays and one who closes the tab without understanding the value.

3. Asking for too much before giving anything

Sign-up forms with twelve fields. Mandatory email verification before seeing anything. A five-step onboarding full of questions the user can’t answer yet.

Every field you ask for before showing value is a reason to leave. Ask yourself what the minimum is for someone to reach their first useful result. You can ask for the rest later, once they understand why it’s worth it.

4. Not defining what “it worked” means

An MVP without a clear metric isn’t an experiment, it’s a bet. If you don’t define in the design which behavior signals success, you won’t know what to measure, and you probably won’t build what’s needed to measure it.

This is a UX decision, not just a business one. If your hypothesis is that users will come back every week, the product needs a reason to come back: a useful notification, a summary, something pending. If you don’t design it, it won’t happen, and you’ll conclude the idea didn’t work when what didn’t work was the product.

5. Treating errors as edge cases

“What if the payment fails?” “What if the connection drops halfway through the form?” “What if they upload the wrong file format?” In an MVP these questions usually get pushed back. But errors aren’t rare: they’re a normal part of use.

An error message that says “Something went wrong” helps nobody. One that says what happened and what the user can do turns a moment of frustration into trust. Designing it is cheap if you do it from the start; adding it later means revisiting every screen.

6. Copying patterns without understanding why they exist

It’s normal to take references from big products. The risk is copying the form without the context. A sidebar with twenty options makes sense in a mature tool with expert users. In an MVP with three features, it only adds noise and makes the product look more complicated than it is.

Before adopting a pattern, ask what problem it solves in the original product and whether you have that same problem. Often the answer is no.

7. Leaving the brand out of the product

Many founders invest in a logo and a polished landing page, and then the product looks like a generic template. Users feel the jump: what the website promised doesn’t match what they find inside.

An MVP doesn’t need a full design system. It needs consistency: the same voice in the copy, the same typography, colors with a logic. That signals there’s a serious team behind it, and in a new product trust is almost everything you have.

How to avoid them without slowing down

None of this takes months of research. It takes order:

  • Write the core flows before designing screens.
  • Design the empty, loading and error states for every key view.
  • Define one or two success metrics and make sure the product can measure them.
  • Test a clickable prototype with five real people before writing code.
  • Make the brand and the product speak the same language from the first version.

The point of an MVP is to spend little to learn a lot. UX mistakes do exactly the opposite: they make you spend later what you didn’t invest earlier. Designing well from the first version isn’t a luxury. It’s the cheapest way to build.