config
Apache 503 Service Unavailable - backend down
AH01114.*HTTP:.*retry|503 Service (Temporarily )?Unavailable
Fixes
- 1.Verify the backend application is running on the ProxyPass target
- 2.Increase ProxyTimeout and timeout settings for slow backends
- 3.Check worker/thread limits in mpm_event/mpm_worker config — may be exhausted under load
apache503proxy
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