428 Precondition Required

This error response indicates that a a precondition must be provided to complete the request.

Precondition headers are often used for file validation, such as with GET or PUT methods. Usually when a server requires precondition headers it is for a file that may have more than one user modifying, as a result preconditions are needed to ensure the files integrity.

This type of error doesn’t usually appear for browser clients.

If this error is unexpected verify the request and appropriate headers. If all conditions are met and the error persists then the server support can help resolve this issue.

The HTTP 428 Precondition Required response status code indicates that the server requires the request to be conditional.

Typically, this means that a required precondition header, such as If-Match, is missing.

When a precondition header is not matching the server side state, the response should be 412 Precondition Failed.