Next.js + Tailwind CSS v4 Issues: Complete Troubleshooting Guide 2024

Anmol
July 31, 2025

Next.js + Tailwind CSS v4 Issues: Complete Troubleshooting Guide 2024

Are your Tailwind v4 styles breaking in Next.js? You're not alone. Here's the complete fix guide that saved thousands of developers.

Table of Contents

  1. Introduction: The v4 Migration Reality
  2. Most Common Issues & Quick Fixes
  3. File Structure & Import Problems
  4. Configuration Conflicts
  5. Production Build Failures
  6. Advanced Troubleshooting
  7. Prevention Tips

Introduction: The v4 Migration Reality

Tailwind CSS v4.0 brought revolutionary changes - 5x faster builds, zero configuration, and modern CSS features. But for Next.js developers, the migration has been anything but smooth.

The harsh truth? Most developers are "vibe coding" their way through the upgrade, hitting walls at every turn. From broken padding/margin utilities to complete style failures in production, the v4 + Next.js combo has left many scratching their heads.

This comprehensive guide covers every major issue developers face when combining Next.js with Tailwind v4, plus the exact fixes that actually work.

Most Common Issues & Quick Fixes

🚨 Issue #1: Padding & Margin Classes Not Working

Symptoms:

  • px-4, py-8, m-4 classes don't apply
  • Elements have no spacing despite Tailwind classes
  • Works in development, fails in production

Root Cause: Tailwind v4's new cascade layer system conflicts with reset styles.

✅ Fix:

/* globals.css - CORRECT v4 setup */
@import "tailwindcss";

@layer base {
  *, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
}

❌ Wrong (causes conflicts):

/* This breaks v4 */
* {
  margin: 0;
  padding: 0;
}
@import "tailwindcss";

🚨 Issue #2: Filename & Import Errors

Symptoms:

  • No Tailwind styles showing at all
  • "Module not found" errors
  • Classes appear in DevTools but no styling

Root Cause: Tailwind v4 is stricter about file naming and imports.

✅ Fix Options:

Option A: Correct Filename (some cases require global.css):

app/
├── global.css     ✅ (singular)
└── layout.tsx

Option B: Standard Filename (globals.css):

app/
├── globals.css    ✅ (plural - most common)
└── layout.tsx

Critical: Ensure import in layout.tsx:

import './globals.css' // or './global.css'

🚨 Issue #3: Wrong Import Syntax

Symptoms:

  • Styles randomly stop working
  • Build errors about directives
  • CSS not processed correctly

Root Cause: Using old v3 syntax in v4.

✅ Correct v4 Syntax:

/* globals.css */
@import "tailwindcss";

@theme {
  --font-family-sans: 'Inter', ui-sans-serif, system-ui;
  --color-primary: #3b82f6;
}

❌ Old v3 Syntax (breaks in v4):

/* DON'T USE - v3 only */
@tailwind base;
@tailwind components;
@tailwind utilities;

File Structure & Import Problems

The Content Path Nightmare

Issue: Tailwind v4's automatic content detection sometimes misses files.

✅ Manual Content Configuration:

/* globals.css */
@import "tailwindcss";

@source "./components/**/*.{js,ts,jsx,tsx}";
@source "./app/**/*.{js,ts,jsx,tsx}";
@source "./pages/**/*.{js,ts,jsx,tsx}";
@source "./src/**/*.{js,ts,jsx,tsx}";

Folder Structure Issues

Common Problem: New folders not being scanned.

Examples of missed paths:

  • ./providers/**/*.tsx
  • ./layouts/**/*.tsx
  • ./hooks/**/*.ts
  • ./utils/**/*.ts

✅ Fix: Add @source directives for all component folders.

Configuration Conflicts

PostCSS Configuration Errors

Issue: Conflicting PostCSS setups between v3 and v4.

✅ Clean v4 PostCSS Config:

// postcss.config.js
module.exports = {
  plugins: {
    tailwindcss: {},
    autoprefixer: {},
  },
}

❌ Don't mix v3 plugins:

// Causes conflicts in v4
module.exports = {
  plugins: {
    'postcss-import': {},
    'tailwindcss/nesting': {},
    tailwindcss: {},
  },
}

Next.js Config Problems

Issue: Turbopack conflicts with Tailwind v4.

✅ Vite Plugin (Recommended):

// next.config.js
/** @type {import('next').NextConfig} */
const nextConfig = {
  // Remove experimental turbopack for v4 compatibility
  experimental: {
    // turbopack: false, // Disable if having issues
  },
}

module.exports = nextConfig;

Production Build Failures

The ".next Folder Cache Issue"

Symptoms:

  • Styles work in dev, fail in production
  • Build succeeds but styles missing
  • Inconsistent styling across deploys

✅ Cache Clearing Fix:

# Clear Next.js cache
rm -rf .next
rm -rf node_modules/.cache

# Rebuild
npm run build

Purge/Content Detection Issues

Issue: Dynamic classes get purged in production.

✅ Safelist Critical Classes:

@import "tailwindcss";

/* Force include dynamic classes */
@source "./components/**/*.{js,ts,jsx,tsx}";

@layer utilities {
  /* Safelist pattern for dynamic classes */
  .text-white,
  .bg-blue-500,
  .p-4,
  .m-4 {
    /* These won't be purged */
  }
}

Advanced Troubleshooting

Theme Configuration Errors

Issue: Custom themes breaking in v4.

❌ Old v3 Config:

// tailwind.config.js (v3)
module.exports = {
  theme: {
    extend: {
      colors: {
        primary: '#3b82f6',
      },
    },
  },
}

✅ New v4 CSS Config:

/* globals.css */
@import "tailwindcss";

@theme {
  --color-primary: #3b82f6;
  --color-secondary: #64748b;
  --font-family-sans: 'Inter', ui-sans-serif, system-ui;
}

Plugin Compatibility Issues

Problem: Many v3 plugins break in v4.

✅ v4 Compatible Setup:

@import "tailwindcss";

/* Replace old plugins with CSS */
@layer utilities {
  .animate-pulse {
    animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
  }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

Shadcn/UI Integration Problems

Issue: Shadcn components break with v4.

✅ Updated Shadcn Setup:

/* globals.css */
@import "tailwindcss";

@theme {
  --color-background: 0 0% 100%;
  --color-foreground: 222.2 84% 4.9%;
  --color-primary: 222.2 47.4% 11.2%;
  --color-secondary: 210 40% 96%;
  --color-border: 214.3 31.8% 91.4%;
  --border-radius: 0.5rem;
}

.dark {
  --color-background: 222.2 84% 4.9%;
  --color-foreground: 210 40% 98%;
}

Prevention Tips

Before You Migrate

  1. Backup your current setup - seriously
  2. Test in a separate branch - v4 can break things
  3. Check plugin compatibility - most need updates
  4. Verify Node.js version - v4 requires Node 18+

Migration Checklist

✅ File Structure:

  • ☐ Correct CSS filename (globals.css or global.css)
  • ☐ Proper import in layout file
  • ☐ All component folders covered by @source

✅ CSS Configuration:

  • ☐ Replace @tailwind with @import "tailwindcss"
  • ☐ Move theme config from JS to CSS
  • ☐ Wrap reset styles in @layer base

✅ Build Process:

  • ☐ Clear .next cache
  • ☐ Update PostCSS config
  • ☐ Test both dev and production builds

Monitoring & Debugging

Enable Debug Mode:

DEBUG=* npm run dev

Check Generated CSS:

# Inspect the actual CSS output
cat .next/static/css/*.css | grep "your-class"

Browser DevTools:

  • Check if classes are in the DOM
  • Verify CSS is loading
  • Look for console errors

Conclusion

Tailwind CSS v4 + Next.js can be powerful, but the migration path is fraught with pitfalls. The key issues are:

  1. Layer system conflicts - wrap reset styles properly
  2. Import syntax changes - use @import "tailwindcss"
  3. File naming strictness - ensure correct imports
  4. Cache problems - clear .next regularly
  5. Production differences - test builds thoroughly

The Bottom Line: If you're having issues, start with the basics - file imports, CSS syntax, and cache clearing. These fix 90% of problems.

Still having issues? Consider sticking with v3.4 until v4 matures. Many production apps have downgraded after hitting too many walls.

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