← All Status Codes
409
Conflict
⚠️ Client Error
Medium Risk
📖 What Is HTTP 409?
The request conflicts with the current state of the target resource. Often occurs with concurrent edits or version mismatches.
🛡️ Security Implications
Race condition indicator. Ensure atomic operations for resources that can be modified concurrently.
🔍 Common Causes
Concurrent modification of the same resource, version conflict in optimistic locking, duplicate resource creation attempt.
🔧 How to Fix
Implement optimistic locking with ETags. Retry the request after fetching the latest version. Use unique constraints in the database.
🖥️ How to Check
curl -I -o /dev/null -w "%{http_code}" https://example.com