It also explains how overusing default components, ignoring accessibility, and misusing Tailwind can impact your project as it grows.
Each mistake is paired with a clear, practical fix so you can improve your workflow, write cleaner UI code, and build scalable interfaces without relying too much on AI-generated solutions.
shadcn/ui is not a traditional component library. You own the code. That is the whole point. The tricky part is that nothing in shadcn/ui stops you from doing it wrong. No warnings, no structure enforced. Mistakes slip in quietly.
These are the 12 that show up most often.
1. Treating shadcn/ui Like a Plug-and-Play Library
shadcn/ui is not npm installed and done. The components live in your codebase. You are responsible for updates, structure, and consistency. Developers who treat it like MUI or Ant Design end up with a mess of unconnected components with no shared logic.
2. Breaking Component Composition Rules
shadcn/ui components are built to be composed together. A common mistake is pulling out a single sub-component and using it in isolation without the parent wrapper, or wrapping components in extra divs that break the intended structure.
For example, using DialogContent without DialogRoot will not throw an obvious error but will break the open and close behavior entirely.
3. Ignoring Accessibility (ARIA and Keyboard Support)
Radix Ui and Base UI handles most accessibility for you. The problem starts when you customize things. Change a trigger, add a wrapper div, swap a slot element, and suddenly keyboard navigation stops working. You did not break it on purpose. You just did not check.
- Replacing a trigger element without keeping the correct role
- Adding a custom wrapper div that shifts focus management
- Removing aria-label from icon-only buttons
4. Misusing Tailwind CSS
Because shadcn/ui uses Tailwind, developers sometimes pile utility classes directly onto components without structure. The result is components that are hard to read, impossible to maintain, and inconsistent across pages.
Two specific patterns to avoid:
- Using arbitrary values like w-[347px] everywhere instead of spacing tokens
- Overriding component styles with !important inside className props
5. Not Using CVA (class-variance-authority) Correctly
shadcn/ui uses CVA to manage component variants. A common mistake is ignoring CVA and instead writing long conditional class strings inline. Fine for one variant. Once you hit three or four, the inline logic becomes difficult to read and easy to break. The other issue is writing the same variant logic in two or three different files. It drifts out of sync and nobody notices until something looks wrong in production.
6. Copy-Pasting Components Without Proper Structure
shadcn/ui encourages you to copy component code into your project. Most people paste it in, see it render, and move on. The issue is that shadcn/ui components often have dependencies, default behaviors, and placeholder logic baked in that you are now responsible for. A component that looks fine on screen can have broken form handling or wrong ARIA labels sitting quietly inside it.
7. Over-Customizing Too Early
A lot of developers start modifying shadcn/ui components the moment they add them. New colors, custom animations, restructured markup. Then requirements change and the heavily customised component needs to be rebuilt from scratch.
Start with the default component. Get it into your layout, connect your data, and test the behavior. Only then decide what visual changes are actually needed.
8. Ignoring Responsive Design
shadcn/ui components are not automatically responsive. Dialogs that look fine on desktop can overflow on mobile. Tables without horizontal scroll become unusable on smaller screens. Developers building on large monitors often miss this entirely.
- Test every component at 375px, 768px, and 1280px
- Use Tailwind responsive prefixes (sm:, md:, lg:) from the start, not as an afterthought
- Wrap wide components like Table and Dialog in containers that handle overflow correctly
9. Skipping Testing
Because you own the component code, bugs in shadcn/ui components are your bugs. Developers who skip testing assume the components work correctly after customisation. They often do not.
What breaks most often after customisation:
- Open and close behavior in Dialogs and Sheets after wrapper changes
- Form validation states when using custom input wrappers
- Dropdown positioning on pages with overflow hidden containers
10. Ignoring Setup and Configuration
Rushing through the initial setup is a mistake that costs time later. Skipping the components.json configuration, not setting up CSS variables correctly, or using the wrong import aliases means components render incorrectly and are harder to update.
- Always run npx shadcn@latest init before adding any component
- Check that your CSS entry file includes the correct @source directives for your content paths
- Set up your CSS variables for light and dark mode from the beginning, not after the fact
11. Over-Relying on AI Code
AI tools can generate shadcn/ui components quickly. Generated code looks correct at a glance. The import paths are often outdated, props get skipped, and the component API may not match the version you are running. These bugs do not crash anything immediately. They show up later, in edge cases, and by then nobody remembers where that component came from.
12. Not Maintaining UI Consistency Across Pages
Different developers adding components in different ways leads to inconsistency. One page uses a filled button, another uses outline. One modal has a close icon, another does not. Individually these seem minor. Across a full product, they make the UI feel unfinished.
- Define a shared set of button variants and stick to them
- Document which components are used for which purpose, even if it is just a short internal note
- Do a visual audit across all pages before every major release
The Bottom Line
Most of these mistakes come from the same place: treating shadcn/ui like a library you consume rather than code you own.
Once that clicks, the right approach to setup, structure, testing, and consistency becomes obvious. You are not using a tool. You are maintaining a codebase.
Read the component. Understand it. Then ship it.
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