Articles & Guides
Useful resources for web developers and system administrators
Found 36 · HTTP · Reset
HTTP
PHP-FPM and 502: queue, pm.max_children and pool sizing
See how a saturated PHP-FPM pool can contribute to 502 or 504. Inspect logs and the listen queue, then estimate pm.max_children from available memory.
HTTP
nginx upstream timed out (110): which timeout to inspect
Diagnose nginx upstream timed out (110) by phase: connect, send or read. Correlate error logs, upstream timing and configuration before changing timeouts.
HTTP
Keep-alive across CDN, load balancer, nginx and app
A mismatched idle timeout across proxies can reset reused connections and sometimes surface as 502. Trace the connection owner, logs and timeout settings.
HTTP
HTTP 500 vs 502 vs 503 vs 504: Find the Failing Hop
Distinguish HTTP 500, 502, 503 and 504 across an edge, proxy and app. A local two-hop lab shows which component emitted each code and where to check logs.
HTTP
curl Timing Breakdown: DNS, TCP, TLS, TTFB and Total Time
Use curl -w to locate slow DNS, TCP, TLS, first-byte and download phases. Three measured sites show why timing fields are cumulative and redirects need care.
HTTP
Cloudflare Error 524 A Timeout Occurred: Causes and Fixes
Error 524 means your origin accepted Cloudflare's connection but sent no response within 125 seconds. Find the slow request, fix it, and compare codes 520–526.
HTTP
HTTP 413 Request Entity Too Large: Which Layer Rejected It
Five components each enforce their own body-size limit, and one of them returns an empty form instead of a 413. Find the narrowest gate before editing configs.
HTTP
Nginx 499 Client Closed Request: What It Means and What to Fix
499 is a log entry, not a status code, and nobody ever receives one. The duration distribution splits timeout misconfiguration from a genuinely slow upstream.
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ERR_HTTP2_PROTOCOL_ERROR: Why It Is Almost Never Your Browser
Chrome aborts on an invalid HTTP/2 frame, so cache and browser tips miss the cause. One protocol comparison separates server, network and client in seconds.
HTTP
Cloudflare Error 530 and 520–526: What Each Code Means
Cloudflare 520-530 errors decoded: 521 refused, 522 timeout, 524 slow origin, 525/526 TLS, 530 with a 1xxx error like 1016 origin DNS.