Root Cause Diagnosis Cloudflare’s authoritative nameservers apply record changes globally within seconds. What you see as “propagation delay” is downstream caching: recursive resolvers, operating systems, and browsers keep serving the old answer until its TTL expires. Gray-clouded (DNS-only) records expose the real origin value and use the TTL you set (Auto = 300 seconds), so any … Read more
Root Cause Diagnosis Nginx returns 413 Request Entity Too Large when the request’s Content-Length exceeds client_max_body_size in the active scope. The log line is client intended to send too large body: N bytes. Nginx’s built-in default is 1 MB, and aaPanel’s shipped nginx.conf typically sets 50 MB. The limit applies wherever the upload request passes through Nginx: the panel behind a reverse proxy or … Read more
Root Cause Diagnosis Error 525 means Cloudflare’s edge connected to the origin on TCP 443 but the TLS handshake failed before any HTTP exchange. With an Origin CA certificate, this almost always means the origin is not presenting a certificate for that connection: no SSL vhost on 443, a certificate and key that do not … Read more
Root Cause Diagnosis DSN code 4.3.0 is a generic, temporary “mail system” status. Postfix emits it when a local dependency fails mid-transaction rather than because of anything wrong with the message or the remote server. On CyberPanel the cause is almost always one of three: the queue or mail store cannot be written (disk full, … Read more
Root Cause Diagnosis Nginx returns 502 when it cannot obtain a valid HTTP response from the upstream. In aaPanel reverse proxy setups with SSL and WebSockets, this comes from one of four causes: the upstream port is not listening, the proxy_pass scheme (http:// vs https://) does not match what the backend speaks, the Upgrade/Connection headers are missing or malformed so the … Read more