TS2307: Cannot find module - in CI

tsc could not resolve an import to a module or to type declarations for it.

What this error means

Type-checking fails with TS2307 naming the import that could not be resolved. It is deterministic and reproduces every run.

src/app.ts(3,21): error TS2307: Cannot find module './utils' or its corresponding type declarations.

Common causes

How to fix it

Install the package and its types

1. Add the dependency and, if it ships no types, its @types package
2. Commit the lockfile so CI installs the same tree

npm i lodash
npm i -D @types/lodash

Configure path aliases and moduleResolution

1. Declare baseUrl and paths in tsconfig
2. Pick a modern moduleResolution (bundler or nodenext)

{
  "compilerOptions": {
    "baseUrl": ".",
    "moduleResolution": "bundler",
    "paths": { "@/*": ["src/*"] }
  }
}

Fix path casing for Linux runners

1. CI runs on case-sensitive Linux; match the exact filename case in the import

How to prevent it

• Install @types for any untyped dependency, keep tsconfig paths in sync with your bundler aliases, and run tsc --noEmit in CI.

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