Client Error (4xx)
HTTP 401 — 401 Unauthorized
Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided.
Common Causes & Diagnoses
- •Missing Authorization header, expired JWT token, invalid API key.
Spesifikasyon & Kategori
Status Code:401
Category:Client Error (4xx)
RFC Standard:RFC 9110 / HTTP/1.1 & HTTP/2
Multi-Language Code Implementations
How to Handle, Return & Test HTTP 401
Status: 401 401 Unauthorized
server.js / handler.ts
// Express.js Server Response
app.get('/api/resource', (req, res) => {
// Returning 401 401 Unauthorized
return res.status(401).json({
error: '401 Unauthorized',
statusCode: 401,
timestamp: new Date().toISOString()
});
});
// Client-side fetch error check
const response = await fetch('/api/resource');
if (response.status === 401) {
console.warn('Received HTTP 401 401 Unauthorized');
}💡 Pro Tip: Ensure appropriate error handling middleware or proxy interceptors are enabled so client applications receive structured JSON responses for HTTP 401.
How to Fix / Practical Code Solutions
Check Bearer Token
Ensure client sends Authorization: Bearer <token>.
if (!authHeader) return res.status(401).json({ error: "Missing Bearer token" });Other Popular HTTP Status Codes
Frequently Asked Questions
Common Questions About HTTP 401 to RFC Standard
Everything you need to know regarding specifications, syntax, and security best practices.
Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided. In Turkish: Kaynağa erişmek için geçerli bir kimlik doğrulama belirteci (token/şifre) gereklidir.