428
428 Precondition Required Error
What This Error Means
The 428 Precondition Required error indicates that the origin server requires the request to be conditional. This is used to prevent the 'lost update' problem, where a client GETs a resource's state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.
Common Causes
- Missing 'If-Match' or 'If-Unmodified-Since' headers in the request.
- Server configuration requiring strict concurrency control.
- API client ignoring conditional requirements.
How to Fix It (For Users)
- 1 This is a technical error usually handled by the application, not the end user.
For Site Owners / Developers
- Ensure your API clients are sending the necessary conditional headers.
- Update documentation to specify required headers.
- Check if a proxy is stripping headers.
When It Is NOT Your Fault
If the server is misconfigured to require conditions for safe methods.
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