# `Module not found: Error: Can't resolve './components/Button' in '/vercel/path0/app'`

**Where it appears:** Vercel build logs (works locally, fails on Vercel)

**What it means:** The uppercase/lowercase letters in an `import` path don't exactly match the file's real name. Mac and Windows ignore case, but Vercel's Linux servers require an exact match.

## Likely causes

- Importing `./components/Button` when the file on disk is named `button.tsx`.
- Renaming a file from `Header.tsx` to `header.tsx` without using `git mv`, so Git kept the old casing.

## Message for your agent

```text
The build works on my computer but fails on Vercel with `Module not found`. Check the exact uppercase/lowercase filename in Git (`git ls-files`) against the import path and fix it.
```

**Prevention:** Name component and utility files consistently in lowercase with hyphens (`user-card.tsx`).

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Source: [Agentic Makers](https://agenticmakers.app/en/help/errors/case-sensitive-import-failed-on-vercel) · License: CC BY 4.0