HTTP 204 No Content vs 521 Web Server Is Down
HTTP 204 (No Content) is a 2xx Success response, while 521 (Web Server Is Down) is a 5xx Server Error response. 204 indicates that the server successfully processed the request but is not returning any content. Common for DELETE operations and form submissions that don't need a response body. In contrast, 521 means that cloudflare-specific. The origin server refused the connection.
Descrição
The server successfully processed the request but is not returning any content. Common for DELETE operations and form submissions that don't need a response body.
Quando você o vê
After DELETE requests, PUT updates where no body is needed, or CORS preflight responses.
Como corrigir
No fix needed. The action was successful; there is simply no content to return.
Descrição
Cloudflare-specific. The origin server refused the connection.
Quando você o vê
When Cloudflare can't establish a TCP connection to the origin server.
Como corrigir
Check that the origin server is running and the firewall allows Cloudflare IPs.
Diferenças principais
204 is a 2xx Success response, while 521 is a 5xx Server Error response.
HTTP 204: The server successfully processed the request but is not returning any content. Common for DELETE operations and form submissions that don't need a response body.
HTTP 521: Cloudflare-specific. The origin server refused the connection.
You encounter 204 when after DELETE requests, PUT updates where no body is needed, or CORS preflight responses.
You encounter 521 when when Cloudflare can't establish a TCP connection to the origin server.
Quando usar qual
For 204 (No Content): No fix needed. The action was successful; there is simply no content to return. For 521 (Web Server Is Down): Check that the origin server is running and the firewall allows Cloudflare IPs.