Ok so here is the situation, we currently have a server and we are now migrating to AWS. We have somehow identical configuration and we already tried to run apache benchmark so the PHP-FPM pool is somehow optimize as far as I know. But after we point the domain in the AWS DNS after an hour we are getting 502 bad gateway and is receiving this error:

connect() to unix:/var/run/nginx/php-fpm.sock failed (11: Resource temporarily unavailable) while connecting to upstream, client:, server: domain.com, request: \"GET / HTTP/1.0\", upstream: \"fastcgi://unix:/var/run/nginx/php-fpm.sock:\", host: \"domain.com\""

Do you have an idea what is wrong in here? Or are there any way to trace which is the one who is causing the 502 bad gateway?


- EC2: m4.large
  - CPU: 2
  - RAM: 8
- Cloudfront
  - min: 2 instances
- Memcached (AWS Elasticache) for PHP session handling


Running in AWS using: CloudFront - ELB - NGINX - PHP

  1. NGINX 1.8
  2. PHP 7.1.11



worker_processes auto;
worker_connections 4096;
multi_accept on;
use epoll;
send_timeout 3600;
fastcgi_buffers 8 128k;
fastcgi_buffer_size 128k;
fastcgi_connect_timeout 600;
fastcgi_send_timeout 600;
fastcgi_read_timeout 3600;
gzip on;


user = nginx
group = nginx
listen = /var/run/nginx/php-fpm.sock
pm = dynamic
pm.max_children = 46
pm.start_servers = 5
pm.min_spare_servers = 3
pm.max_spare_servers = 5
request_terminate_timeout = 3600
pm.max_requests = 400
process.priority = -19
request_terminate_timeout = 3600
catch_workers_output = yes
  • That URL "fastcgi://unix:(etc)" looks fishy to me. Double check the URL, and if you can't get Unix sockets working try http sockets. – Tim Nov 28 '17 at 8:14
  • I already check the unix sockets and the same configuration works on different website with the exact same configuration. – Rei Nov 28 '17 at 8:27
  • Are both servers using exactly the same version of the same operating system? Things can change, or be set up differently. I'm 70% sure the problem is connecting Nginx to PHP, just try different approaches until one works. – Tim Nov 28 '17 at 18:22
  • I'm using saltstack to setup the configuration so I am 100% sure that they have the same configuration or setup. – Rei Nov 30 '17 at 19:21
  • 1
    Is it possible that the problem is in the performance of S3Fuse? Cause we are using a php script to scan the directory. – Rei Dec 1 '17 at 7:56

Found the problem last year. Just want to share what I found out. It was due to S3Fuse + PHP script that will scan through the folder where S3Fuse is being mounted. It get's a lot of load. S3Fuse is so slow for scanning through the files, especially if you have so much files in the bucket.

I think it is recommended to use S3Fuse if you will only use it for reading files or for backing up files. The alternative that you can use in AWS for multi-mounted storage is EFS.


Step 1: Some Missing Configuration, Please add in your PHP_FPM File

listen.allowed_clients =

listen.owner = nginx
listen.group = nginx
listen.mode = 0666

Step 2: Depends on PHP Version sometimes php-fpm.sock name can be php5-fpm.sock. Please make sure the socket name is same in nginx and php-fpm configuration.

Hope that will solve your issue immediately.

  • Hey, thanks for the answer, but I already tried that and it didn't work. Although interestingly, after I fire a script - session_destory - it takes me to cloudfront error and now I'm getting 502 bad gateway or the page would not load. – Rei Nov 30 '17 at 19:23

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