Next.js tsconfig path alias "@/..." not resolved in CI

Next.js reads compilerOptions.paths and baseUrl from tsconfig.json to resolve aliases like @/. If those are missing, mistyped, or point at a path whose case differs on Linux, the alias fails to resolve during next build.

What this error means

next build fails with "Module not found: Can't resolve '@/components/Button'" while the dev server resolved it, typically because tsconfig paths are absent or the target case differs in CI.

next build

./app/page.tsx
Module not found: Can't resolve '@/components/Button'

https://nextjs.org/docs/messages/module-not-found

Common causes

baseUrl or paths is missing in tsconfig

Next relies on the tsconfig mapping to expand @/; without baseUrl and a paths entry the alias is unresolvable.

The aliased target has a case mismatch on Linux

The alias resolves to a path whose directory or file case differs from the committed name, which only fails on the case-sensitive runner.

How to fix it

Define baseUrl and paths in tsconfig

Set baseUrl and add a paths mapping for the alias prefix.
Confirm the target case matches the committed file names.
Re-run next build.

tsconfig.json

// tsconfig.json
{ "compilerOptions": {
    "baseUrl": ".",
    "paths": { "@/*": ["./*"] }
} }

Fix any case mismatch in the resolved path

Make the alias target match the committed casing exactly so the Linux runner resolves it.

How to prevent it

Keep tsconfig paths and baseUrl in sync with your alias usage.
Match import case to committed file names for Linux CI.
Run a Linux build before merge to catch alias and case issues.