Heads up! Long post and lots of head bashing against the wall. Context: I have a written an a python app (Django). I have dockerized the deployment and the compose file has three containers, app, nginx and postgres. I'm currently trying to deploy a demo of it in a VPS running Debian 11. Information below has been redacted (IPs, Domain name, etc.) Problem: I keep running into 502 errors. Locally things work very well even with nginx (but running on 80). As I try to deploy this I'm trying to configure nginx the best I can and redirecting http traffic to https and ssl certs. The nginx logs simply say "connect() failed (111: Connection refused) while connecting to upstream, client: 1.2.3.4, server: demo.example.com, request: "GET / HTTP/1.1", upstream: "http://192.168.0.2:8020/", host: "demo.example.com"". I have tried just about everything. What I've tried: - Adding my server block configs to /etc/nginx/conf.d/default.conf - Adding my server block configs to a new file in /etc/nginx/conf.d/app.conf and leaving default at out of box config. - Tried putting the above config (default.conf and app.conf) in sites-available (/etc/nginx/sites-available/* not at the same time tho). - Recreated /etc/nginx/nginx.conf by copy/pasting out of box nginx.conf and then adding server blocks directly in nginx.conf - Running nginx -t inside of the nginx container (Syntax and config were "successful") - Running nginx -T when recreated /etc/nginx/nginx.conf - nginx -T when the server blocks where in /etc/nginx/conf.d/* lead me to think that since there were two server listen 80 blocks that I should ensure only one listen 80 block was being read by the container hence the recreated /etc/nginx/nginx.conf from above - Restarted container each time a change was made. - Changed the user block from nginx (no dice when using nginx as user) to www-data, root and nobody - Deleted my entire docker data and redeployed everything a few times. - Double checked the upstream block 1,000 times - Confirmed upstream block container is running and on the right exposed port Checked access.log and error.log but they were both empty (not sure why, tried cat and tail) - Probably forgetting more stuff (6 hours deep in the same error loop by now) How can you help: Please take a look at the nginx.conf config below and see if you guys can spot a problem, PLEASE! This is my current /etc/nginx/nginx.conf ` user www-data; worker_processes auto; error_log /var/log/nginx/error.log notice; pid /var/run/nginx.pid; events { worker_connections 1024; } http { include /etc/nginx/mime.types; default_type application/octet-stream; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; access_log /var/log/nginx/access.log main; sendfile on; #tcp_nopush on; keepalive_timeout 65; #gzip on; upstream djangoapp { server app:8020; } server { listen 80; listen [::]:80; server_name demo.example.com; return 301 https://$host$request_uri; } server { listen 443 ssl; listen [::]:443 ssl; server_name demo.example.com; ssl_certificate /etc/letsencrypt/live/demo.example.com/fullchain.pem; ssl_certificate_key /etc/letsencrypt/live/demo.example.com/privkey.pem; #ssl_protocols TLSv1.2 TLSv1.3; #ssl_prefer_server_ciphers on; location / { proxy_pass http://djangoapp; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-Proto $scheme; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; #proxy_set_header Upgrade $http_upgrade; #proxy_set_header Connection keep-alive; proxy_redirect off; } location /static/ { autoindex on; alias /static/; } } } ` - EDIT: I have also confirmed that both containers are connected to the same docker network (docker network inspect frontend) - EDIT 2: Solved my problem. See my comments to @chaospatterns. TLDR there was an uncaught exception in the app but it didn’t cause a crash with the container. Had to dig deep into logs to find it.