Django deploy with Gunicorn, Nginx and Docker-Compose returns Server Error 500

I'm deploying a Django application on ubuntu server, where I have installed Nginx. The app is deployed using docker-compose and gunicorn.

Here's my nginx configuration:

upstream backend {
    server 0.0.0.0:8000;
}

server {
    index index.html index.htm index.nginx-debian.html;
    server_name www.example.com example.com;

    location / {
        root /home/user/project/web;
        index  index.html index.htm;
        try_files $uri $uri/ /index.html;
    }

    location /api/ {
        proxy_pass http://backend/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    location /media/ {
        autoindex off;
        alias /home/user/project/backend/media/;
    }

    location /staticfiles/ {
        autoindex off;
        alias /home/user/project/backend/staticfiles/;
    }

    location ~ /\. {
        deny all;
    }
}

And here's my Django views:

def index(request):
    return render(request, "landing.html")

@api_view(["POST"])
@permission_classes([AllowAny])
def create_user(request):
    data = request.data
    ...

So when calling: https://example.com/api/ it works, returning the content of the html file. But when try to call the second view with https://example.com/api/create/ it shows 500 internal server error, and in the docker console I can see the log of the error, so it reach the server.

And finally a slice of my docker-compose file for the django app:

services:
  app:
    build: .
    command: uvicorn real.asgi:application --host 0.0.0.0 --port 8000
    volumes:
      - .:/code
    env_file:
      - ./.env/dev.env
    ports:
      - 8000:8000
    depends_on:
      - database
      - redis