428 Precondition Required

What it means

HTTP 428 Precondition Required means the server refuses an unconditional request and insists the client include a precondition such as If-Match. It exists to close the lost-update gap: without a precondition, two clients can each read a resource and overwrite the other's change. By requiring a condition, the server forces clients to confirm they are editing the version they think they are.

When it happens

It happens with APIs that mandate conditional writes, returning 428 when a PUT or PATCH arrives without an If-Match header so that concurrent edits cannot silently clobber each other.

How to fix it

• Add the required precondition header, typically If-Match with the resource's current ETag.
• Fetch the resource first to obtain a fresh ETag, then send the conditional request.
• Follow the API's documentation for which precondition each write expects.

SEO impact

None directly. It governs conditional API writes and does not affect crawling or indexing of pages.