HTTP 409 Conflict — What It Means and How to Fix It

Common Causes

• Concurrent updates to the same resource (e.g., two users editing the same document simultaneously).
• Violation of a unique constraint (e.g., trying to create a user with an email address that already exists).
• Attempting to perform an operation on a resource that is in an invalid state for that operation (e.g., deleting a non-empty directory without specifying a recursive delete).
• Version mismatch, often indicated by an `If-Match` header failing.

Code Examples to Handle HTTP 409

curl -I https://httpbin.org/status/409

fetch('https://httpbin.org/status/409')
  .then(response => {
    if (response.status === 409) {
      console.log('Handled Conflict');
    }
  });

import requests

response = requests.get('https://httpbin.org/status/409')
if response.status_code == 409:
    print("Received Conflict")

How to Fix It

1. Review the response body for specific details about the conflict, as the server should provide information on why the request failed.
2. If the conflict is due to concurrent updates, retrieve the latest version of the resource, merge changes if necessary, and then re-attempt the request.
3. If a unique constraint is violated, modify the request payload to ensure uniqueness (e.g., provide a different email address).
4. For version conflicts, ensure the `If-Match` header (if used) contains the correct ETag for the current resource state.

Related Status Codes