Build Failures and Dependency Hell: Why Your Deploy Keeps Failing

Your app works perfectly in Bolt or v0. You hit "Deploy" with confidence. Then you watch in horror as the build log fills with red error messages: Module not found, TypeScript error TS2345, peer dependency conflict, and finally Build failed. Welcome to dependency hell.

The Package Manager War

One of the most frustrating issues with AI-generated projects is package manager confusion. Your project might be configured for npm, but the AI tool used yarn, or you have both package-lock.json and yarn.lock in your repo, causing cryptic errors.

The Symptoms

# Build fails with mysterious errors
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree

# Or references to yarn even though you're using npm
Error: ENOENT: no such file or directory, open '/app/yarn.js'

Why This Happens

AI coding assistants often:

• Copy examples from different package managers
• Install packages with whatever tool is available
• Generate lockfiles for multiple package managers
• Don't specify which package manager to use

The Solution

Pick one package manager and stick with it:

# If using npm, delete yarn files
rm yarn.lock
rm -rf node_modules
npm install

# If using yarn, delete npm files
rm package-lock.json
rm -rf node_modules
yarn install

# If using pnpm
rm package-lock.json yarn.lock
rm -rf node_modules
pnpm install

Specify in package.json:

{
  "packageManager": "npm@10.2.0",
  "engines": {
    "node": ">=20.0.0",
    "npm": ">=10.0.0"
  }
}

Configure your deployment platform to use the correct package manager in build settings.

The "Missing Dependency" Mystery

Your build fails with Cannot find module 'react-icons' even though it's listed in your package.json. What gives?

Common Causes

1. Dependency in Wrong Section

{
  "devDependencies": {
    "react-icons": "^5.0.0"  // ❌ Used in production code
  }
}

Build systems often skip devDependencies in production. Move it:

{
  "dependencies": {
    "react-icons": "^5.0.0"  // ✅ Available in production
  }
}

2. Case-Sensitive Import Paths

Works on Windows/Mac, breaks on Linux (where most servers run):

// ❌ File is named Button.tsx
import Button from './components/button';

// ✅ Match exact filename
import Button from './components/Button';

3. Missing File Extensions

// ❌ Might fail in production
import { utils } from './lib/utils';

// ✅ Explicit extension
import { utils } from './lib/utils.ts';

4. Workspace/Monorepo Confusion

AI tools sometimes generate workspace configurations incorrectly:

// ❌ Package not in workspace
{
  "workspaces": ["packages/*"],
  "dependencies": {
    "@myapp/utils": "workspace:*"  // But utils isn't in packages/
  }
}

TypeScript Build Errors That Block Deployment

Bolt.new users report this constantly: AI can't fix TypeScript errors, and the build fails repeatedly with type mismatches.

Classic TypeScript Errors

TS2345: Argument of type 'X' is not assignable to parameter of type 'Y'

// ❌ AI generates this
function greet(name: string) {
  console.log(`Hello ${name}`);
}
greet(undefined); // Error!

// ✅ Handle optional values
function greet(name: string | undefined) {
  if (!name) return;
  console.log(`Hello ${name}`);
}

TS2322: Type 'null' is not assignable to type 'User'

// ❌ AI assumes data always exists
const [user, setUser] = useState<User>(null);

// ✅ Handle null state
const [user, setUser] = useState<User | null>(null);

if (user) {
  console.log(user.name); // Now TypeScript knows user exists
}

TS2741: Property 'id' is missing in type

// ❌ Missing required properties
interface User {
  id: string;
  name: string;
  email: string;
}

const user: User = { name: 'John' }; // Error!

// ✅ Provide all properties or make them optional
interface User {
  id: string;
  name: string;
  email?: string; // Optional
}

The Nuclear Option

If TypeScript errors are blocking deployment and you need to ship NOW:

// tsconfig.json - temporary workaround
{
  "compilerOptions": {
    "skipLibCheck": true,
    "noEmit": false,
    // Last resort: disable strict checks
    "strict": false
  }
}

⚠️ Warning: This is a band-aid. Your app might have runtime errors that TypeScript would have caught. Use only for emergencies, then fix the actual issues.

Peer Dependency Conflicts

npm ERR! peer react@"^18.0.0" from react-router@6.20.0
npm ERR! but you have react@17.0.2 installed

AI tools often mix library versions that aren't compatible.

Quick Fixes

Option 1: Update the dependency

npm install react@18

Option 2: Use --legacy-peer-deps (not recommended)

npm install --legacy-peer-deps

Option 3: Use overrides (npm 8.3+)

{
  "overrides": {
    "react": "^18.0.0"
  }
}

Build Timeouts

Your build starts, runs for 10 minutes, then times out. Common on free tiers of Vercel, Netlify, or Railway.

Why Builds Timeout

1. Installing too many dependencies - AI generates projects with 300+ packages
2. Running expensive build steps - Image optimization, asset compilation
3. Incorrect build command - Running dev server instead of production build
4. No build caching - Reinstalling everything from scratch

Solutions

Optimize dependencies:

# Find large packages
npx npkill
npm ls --all --long

# Remove unused dependencies
npm prune

Configure caching:

# .github/workflows/deploy.yml
- uses: actions/cache@v3
  with:
    path: ~/.npm
    key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}

Speed up builds:

{
  "scripts": {
    "build": "vite build --mode production",
    "build:fast": "vite build --mode production --minify false"
  }
}

The Wrong Output Directory

Build succeeds, but deployment shows a blank page. The build output went to the wrong folder.

Common Mistakes

// vite.config.ts
export default {
  build: {
    outDir: 'dist'  // But Vercel expects 'build'
  }
}

Check your platform's expectations:

• Vercel: Typically dist or .next
• Netlify: dist, build, or public
• Cloudflare Pages: dist
• AWS Amplify: build

Or configure in deployment settings:

# netlify.toml
[build]
  publish = "dist"
  command = "npm run build"

Environment-Specific Build Issues

Builds pass locally but fail in CI/CD.

Common Culprits

1. Different Node versions

# Local: Node 20.10.0
# CI: Node 18.12.0

# Fix: Specify version
# .nvmrc
20.10.0

2. Missing environment variables during build

// ❌ Requires env var at build time
const API_URL = process.env.VITE_API_URL;

// Build fails if VITE_API_URL not set in CI

3. Platform-specific commands

{
  "scripts": {
    // ❌ Won't work on Windows
    "build": "rm -rf dist && vite build"

    // ✅ Cross-platform
    "build": "rimraf dist && vite build"
  }
}

The Bolt.new TypeScript Loop

GitHub Issue #5511: "Bolt can't fix TypeScript errors in the project, which caused build project failure again and again and again..."

This is a known limitation: Bolt's AI sometimes generates code with type errors it can't fix. Users report asking the AI to fix the same error 10+ times with no success.

Workarounds

1. Copy the exact error message into a new chat
2. Specify the file and line number explicitly
3. Ask for the complete file, not just a patch
4. Fix it manually using the code editor
5. Disable strict type checking temporarily (not ideal)

Monorepo and Workspace Nightmares

AI tools struggle with monorepos, often generating incompatible workspace configurations:

// ❌ Mixing workspace protocols
{
  "dependencies": {
    "@myapp/ui": "workspace:*",
    "@myapp/utils": "file:./packages/utils",
    "@myapp/config": "^1.0.0"  // Should also be workspace
  }
}

Fixing Workspace Issues

# Clear everything
rm -rf node_modules packages/*/node_modules
rm package-lock.json packages/*/package-lock.json

# Reinstall from root
npm install

When Builds Get Truly Broken

Sometimes you need to start fresh:

# Nuclear option: Reset everything
git clean -fdx
rm -rf node_modules
rm package-lock.json yarn.lock pnpm-lock.yaml
npm install
npm run build

If that doesn't work, you're likely dealing with:

• Conflicting global packages
• Corrupted npm cache
• Invalid TypeScript configurations
• Framework-specific issues requiring deep expertise

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