5xx series problem solving

5xx Solution of a series of problems

solve 5xx The first means to solve a series of problems is to query nginx Error log .

• 500（ Server internal error ） Server encountered an error , Unable to complete request .
• 501（ Not yet implemented ） The server does not have the function to complete the request . for example , When the server does not recognize the request method , The server may return this code .
• 502 Bad Gateway bad gateway Upstream error php-fpm Not started or not responding correctly .
• 503 service temporarily unavailable In general, it is caused by too many visits to the website , When the number of visits to the website has passed, the website will return to normal
• 504 gateway timeout gateway time-out Upstream timeout php-fpm Execution timeout
• 505（HTTP Version not supported ） The server does not support HTTP Protocol version .

I centos On nginx Of error.log stay var Next

[[email protected] public]$>sudo tailf /var/log/nginx/error.log
...
2020/10/18 20:37:52 [error] 19271#19271: *19 connect() failed (111: Connection refused) while connecting to upstream, client: 127.0.0.1, server: local.laravel.com, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "local.laravel.com"
2020/10/18 20:37:52 [crit] 19271#19271: *19 open() "/var/log/nginx/local.laravel.com.access.log" failed (13: Permission denied) while logging request, client: 127.0.0.1, server: local.laravel.com, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "local.laravel.com"

Written clearly , No response from upstream . It turns out to be php-fpm Didn't start …