Client Error (4xx)

HTTP 428 — 428 Precondition Required

The origin server requires the request to be conditional to prevent the "lost update" problem where multiple clients modify a resource simultaneously.

Common Causes & Diagnoses

•PUT or PATCH request sent without an ETag-based If-Match header.

Spesifikasyon & Kategori

Status Code:428

Category:Client Error (4xx)

RFC Standard:RFC 9110 / HTTP/1.1 & HTTP/2

Multi-Language Code Implementations

How to Handle, Return & Test HTTP 428

Status: 428 428 Precondition Required

server.js / handler.ts

// Express.js Server Response
app.get('/api/resource', (req, res) => {
  // Returning 428 428 Precondition Required
  return res.status(428).json({
    error: '428 Precondition Required',
    statusCode: 428,
    timestamp: new Date().toISOString()
  });
});

// Client-side fetch error check
const response = await fetch('/api/resource');
if (response.status === 428) {
  console.warn('Received HTTP 428 428 Precondition Required');
}

💡 Pro Tip: Ensure appropriate error handling middleware or proxy interceptors are enabled so client applications receive structured JSON responses for HTTP 428.

How to Fix / Practical Code Solutions

Include If-Match Header

Fetch the latest ETag via GET first, then provide If-Match: "etag_value" in your mutation.

Other Popular HTTP Status Codes

100 101 200 201 202 204 206 301 302 304 307 308

Frequently Asked Questions

Common Questions About HTTP 428 to RFC Standard

Everything you need to know regarding specifications, syntax, and security best practices.

The origin server requires the request to be conditional to prevent the "lost update" problem where multiple clients modify a resource simultaneously. In Turkish: Kaynakta çakışmaları ve eşzamanlı üzerine yazmaları önlemek için sunucu If-Match veya If-Unmodified-Since başlığı talep ediyor.