The 412 Precondition Failed error message is a standard HTTP error code.
When parsing a webpage, the web server looks for a precondition specification in the browser's HTTP data: specifically, one or more of the request's header fields. If the precondition is not met in the web page, the server returns the 412 error.
A 412 error is usually caused by a configuration or programming error on the web server, so we recommend that you focus your troubleshooting there.
Refer to the HTTP 1.1 specification for additional information.