Articles/HTTP

HTTP 428 Precondition Required — What It Means

What HTTP status code 428 Precondition Required means, when servers return it, and how to handle it correctly.

Published September 25, 2026

HTTP 428 Precondition Required — The server requires the request to be conditional.

Key points

  • Designed to prevent the "lost update" problem in concurrent editing scenarios
  • Requires clients to use a conditional header like If-Match before allowing an update
  • Without it, two clients could unknowingly overwrite each other's changes
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