Fix Content Security Policy Violation Error in React

What Is the Content Security Policy Violation Error?

If you've encountered the Content Security Policy Violation error in React, you're not alone. This common issue trips up developers during development and deployment alike.

Why It Happens

This happens when the browser blocks resources that violate the CSP headers — scripts, styles, or connections from unauthorized origins.

The Fix

// next.config.js
const cspHeader = [
  "default-src 'self'",
  "script-src 'self' 'unsafe-inline'",
  "style-src 'self' 'unsafe-inline'",
  "connect-src 'self' https://api.example.com",
].join('; ');

module.exports = {
  async headers() {
    return [{
      source: '/(.*)',
      headers: [{ key: 'Content-Security-Policy', value: cspHeader }]
    }];
  }
};

When This Error Appears in Production

If you encounter Content Security Policy Violation in a live React application, the first priority is understanding the blast radius — how many users are affected? Check your error monitoring dashboard for frequency and patterns. Often, this error correlates with specific user actions, browsers, or network conditions. Implementing graceful degradation ensures your application remains usable even when this error occurs. Consider adding a retry mechanism with exponential backoff for transient failures.

Prevention

[Bugsly](https://bugsly.dev) makes tracking errors like this effortless — real-time notifications with complete stack traces.

Key Takeaways

• Always handle this error gracefully with proper error handling
• Check your environment configuration
• Test thoroughly before deploying to production