Google Chrome is Failing to POST: The Mysterious Case of the Low Content-Length Limit

Have you ever encountered an issue where Google Chrome refuses to send a POST request, simply because the Content-Length exceeds a certain, seemingly arbitrary, limit? You’re not alone! In this article, we’ll delve into the mysterious world of Chrome’s Content-Length restriction, explore the reasons behind this behavior, and provide you with practical solutions to overcome this frustrating problem.

What’s the Deal with Content-Length, Anyway?

In HTTP, the Content-Length header specifies the size of the message body in bytes. This allows the server to allocate the necessary resources to handle the incoming request. Sounds simple, right? However, when it comes to Google Chrome, things get a bit more complicated.

The Low Content-Length Limit: A Chrome-Specific Quirk

It’s essential to understand that Chrome has a built-in limit for the Content-Length header. This limit is ridiculously low, often causing issues when sending larger requests. The exact limit varies depending on the Chrome version, but it’s typically around 65,535 bytes (64KB – 1). Yes, you read that right – 64KB minus 1 byte!

Content-Length: 65535 // The magical limit

Why Does Chrome Impose This Limit?

According to the Chromium developers, this limit is enforced to prevent potential security vulnerabilities. The idea is to prevent attackers from sending excessively large requests, which could lead to buffer overflow attacks or denial-of-service (DoS) attacks.

While this motivation is valid, it’s debatable whether a fixed limit is the most effective approach. After all, modern web applications often require sending larger payloads, and this restriction can hinder legitimate use cases.

Symptoms of the Content-Length Limitation

So, how do you know if you’re hitting the Content-Length limit in Chrome? Keep an eye out for these symptoms:

• POST requests fail silently, without any error messages or warnings.
• The request is not sent, or the browser appears to hang.
• The server may receive a truncated or incomplete request.
• ERR_INSUFFICIENT_RESOURCES or ERRaboration is occasionally thrown.

POST /upload HTTP/1.1
Content-Type: application/octet-stream
Transfer-Encoding: chunked

// Chunk 1
4
Hello
// Chunk 2
5
World
// ...
0
// End of chunks

POST /upload HTTP/1.1
Content-Type: application/octet-stream
Transfer-Encoding: streaming

// Stream the data in chunks

server {
    listen 80;
    server_name example.com;

    location /upload {
        // Increase the buffer size to accommodate larger requests
        client_max_body_size 100m;
        client_body_buffer_size 100m;
    }
}

if (isChrome()) {
    var xhr = new XMLHttpRequest();
    xhr.open('POST', '/upload', true);
    xhr.send(blob);
} else {
    fetch('/upload', {
        method: 'POST',
        body: blob
    });
}