When web scraping or sending automated requests, encountering HTTP error 413 can be frustrating. This error occurs when the payload you’re sending exceeds the server’s limit.
In this article, we’ll break down, replicate and test the 413 error. We'll take a look at why it happens, and provide tips on how to manage your payloads efficiently. We’ll also explore how Scrapfly can help you bypass these issues and ensure successful requests.
What is HTTP Error 413?
HTTP error "413 request entity too large occurs" when the server refuses to process a request because the size of the payload (the data being sent) exceeds the server's allowed limits. This often happens when you try to upload large files or send a request with a body that’s too large for the server to handle.
What are HTTP 413 Error Causes?
The most common cause of the 413 error is attempting to send a request with a payload that's too big. This usually happens during POST or PUT requests when you send a large file or data set to a server that has a limit on the size of requests it can accept. Since there isn’t always an endpoint or way to know the size limit in advance, you might hit this error unexpectedly.
To avoid this, make sure to check the size of the payload you're sending and compress or break it into smaller parts if needed.
Practical Example
To demonstrate how a server would return an HTTP 413 status code (Payload Too Large), let's build a simple Flask API with an /upload endpoint that accepts file uploads. We'll set a maximum file size limit to simulate a scenario where the client sends a file that exceeds this limit, triggering a 413 Payload Too Large error.
from flask import Flask, jsonify, request
app = Flask(__name__)
# Set a maximum file size limit (1 MB in this case)
MAX_FILE_SIZE = 1024 * 1024 # 1 Megabyte
@app.route('/upload', methods=['POST'])
def upload_file():
# Check the size of the incoming request
content_length = request.content_length
if content_length is None:
return jsonify({"error": "Content-Length header is missing"}), 411 # 411 Length Required
if content_length > MAX_FILE_SIZE:
return jsonify({
"error": "Payload Too Large",
"message": f"The uploaded file exceeds the maximum allowed size of {MAX_FILE_SIZE / (1024 * 1024)} MB."
}), 413
# Proceed if file is within size limit
if 'file' not in request.files:
return jsonify({"error": "No file part in the request"}), 400
file = request.files['file']
if file:
# Assuming file handling logic goes here, e.g., saving the file
return jsonify({"message": "File uploaded successfully!"}), 200
if __name__ == '__main__':
app.run(debug=True)
In this example, the MAX_FILE_SIZE is set to 1 MB. The /upload endpoint checks the Content-Length header of the incoming request to determine the size of the payload. If the size exceeds the allowed limit, the server responds with a 413 Payload Too Large status code and a message indicating the maximum allowed file size.
If the file size is within the allowed limit, the file is processed successfully, and a 200 OK status is returned. This demonstrates how to handle large payloads and provide appropriate feedback to clients when the file size exceeds the server's limitations.
import httpx
import random
import string
# Function to generate a random string of specified size (in bytes)
def generate_random_string(size_in_bytes):
# Each character is 1 byte, so size_in_bytes equals the number of characters
return ''.join(random.choices(string.ascii_letters + string.digits, k=size_in_bytes))
# Test successful upload (less than 1MB)
def test_successful_upload():
small_file_content = generate_random_string(500 * 1024) # 500 KB file
files = {'file': ('small_file.txt', small_file_content)}
response = httpx.post("http://127.0.0.1:5000/upload", files=files)
print(f"Successful Upload: {response.status_code}, {response.json()}")
# Test failed upload (more than 1MB)
def test_failed_upload():
large_file_content = generate_random_string(2 * 1024 * 1024) # 2 MB file
files = {'file': ('large_file.txt', large_file_content)}
response = httpx.post("http://127.0.0.1:5000/upload", files=files)
print(f"Failed Upload: {response.status_code}, {response.json()}")
if __name__ == "__main__":
test_successful_upload()
test_failed_upload()
Here, we replicated both server and client conditions of status code 413 in Python, Flask server and httpx client.
Can 413 Mean Blocking?
Although HTTP error 413 typically relates to the size of the data being sent, it’s worth noting that error codes are not always used consistently by websites. In rare cases, websites might misconfigure their responses or use 413 as a way to block certain requests.
While it’s unlikely that a 413 error means you’re being blocked, it's still good practice to test the request with rotating proxies or with smaller data. For more blocking bypass try these two popular tools:
curl-impersonate - can enhance cURL client fingerprint to mimic a real web browser.
It takes Scrapfly several full-time engineers to maintain this system, so you don't have to!
Summary
HTTP 413 errors are usually caused by sending a request with a payload that’s too large, but error codes aren’t always accurate and could indicate blocking. By carefully managing your payload size and using tools like Scrapfly to handle retries and proxies, you can overcome these issues and keep your scraping tasks running seamlessly.
