config
HTTP Public Key Pinning validation failure
HPKP.*pin.*validation failed|Public-Key-Pins.*mismatch
Fixes
- 1.HPKP is deprecated — remove Public-Key-Pins header from your server configuration
- 2.If still using HPKP, add a backup pin and ensure the pinned key matches current or backup cert
- 3.Clear the pin in browser by visiting the domain after removing the header (respect max-age expiry)
securityHPKPdeprecated
Related Errors
config3 fixes
Nginx 502 Bad Gateway - upstream unavailable
502 Bad Gateway|upstream prematurely closed connection
- •Verify the upstream server is running and listening on the expected address/port
- •Increase proxy_read_timeout and proxy_connect_timeout for slow backends
config3 fixes
Nginx 504 Gateway Timeout
504 Gateway Time-?out|upstream timed out.*reading response
- •Increase proxy_read_timeout (default 60s): proxy_read_timeout 300s
- •Optimize the backend endpoint that's taking too long to respond
config3 fixes
Nginx redirect loop
rewrite or internal redirection cycle|return 301.*too many redirects
- •Check for conflicting rewrite rules that redirect back and forth (HTTP→HTTPS→HTTP)
- •Use 'return 301' instead of 'rewrite' for simple redirects to avoid rule interaction