415 Unsupported Media Type means the server refused the request because the format of the request body is not supported. In most cases, the URL is correct and the server is reachable, but the body format, Content-Type, Content-Encoding, or upload type does not match what the endpoint expects. This is a request-format problem, not a
405 Method Not Allowed means the server understands the HTTP method, but the specific resource you requested does not allow that method. In simple terms, the URL exists, the server knows what GET, POST, PUT, or DELETE means, but that endpoint is not configured to accept the method you used. This is a configuration or
520 Unknown Error means Cloudflare reached your origin server, but the origin returned something Cloudflare could not interpret as a valid HTTP response. In plain terms, the connection got far enough to touch the server, but the server answered with an empty, malformed, incomplete, or unexpected response. This is why Error 520 is frustrating. It
431 Request Header Fields Too Large means the server refused the request because the HTTP request headers were too large. In real cases, this usually comes from oversized cookies, a bloated Referer, too many custom headers, or header limits that are too strict on the server or proxy. :contentReference[oaicite:1]{index=1} This is not usually a mystery
414 Request-URI Too Long means the server refused the request because the URL was too long to process. In most cases, the problem is not the page itself. It is the request format, the query string, a redirect loop, or an application that keeps adding data to the URL. This error is common on search
408 Request Timeout means the server gave up waiting for the client to finish sending the request. In simple terms, the connection started, but the full request did not arrive in time. This is not always a server crash. In many real cases, the server is working, but the request was too slow, incomplete, interrupted,
429 Too Many Requests means the server is refusing requests because too many were sent in a short period of time. The site may still be online and healthy, but it is rate-limiting you, your browser, your bot, your plugin, or your application. This is not the same as a total server outage. In most
Upstream Timeout Error occurs when a proxy or gateway server waits too long for a response from an upstream server. The request reaches the gateway successfully, but the backend service does not respond within the configured timeout period. When that limit is exceeded, the gateway stops waiting and returns a timeout error. Quick Fix Reload
500 Internal Server Error means the server failed while processing the request. The request reached the server successfully, but something inside the application or server configuration broke. The error is intentionally generic. It indicates that the server encountered an unexpected condition and could not return a valid response. Quick Fix Reload the page after a
504 Gateway Timeout means a server acting as a gateway or proxy did not receive a response from the upstream server in time. The request reaches the gateway server, but the backend service takes too long to respond. When the timeout limit is exceeded, the gateway stops waiting and returns a 504 error. Quick Fix