[Python] PostgreSQL 15 protocol version error with Django and psycopg2 in Docker environment

I'm experiencing protocol version errors while running a Django application with PostgreSQL 15 in Docker containers:

FATAL: unsupported frontend protocol 0.0: server supports 3.0 to 3.0
FATAL: unsupported frontend protocol 255.255: server supports 3.0 to 3.0
FATAL: no PostgreSQL user name specified in startup packet


My setup:

• Django 4.2.16
• PostgreSQL 15
• psycopg2-binary 2.9.10
• Python 3.11.4

Docker Compose configuration:

services:
postgres:
image: postgres:14
container_name: postgres
volumes:
- postgres_data:/var/lib/postgresql/data/
environment:
- POSTGRES_USER=${POSTGRES_USER}
- POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
- POSTGRES_DB=${POSTGRES_DB}
ports:
- "5432:5432"

backend:
build:
context: ./core
dockerfile: Dockerfile.prod
container_name: backend
volumes:
- ./core:/home/app/core
- static_volume:/home/app/core/static
- media_volume:/home/app/core/media
expose:
- "8000"
environment:
# role for entrypoint
- ROLE=backend
# basic settings
- SECRET_KEY=${SECRET_KEY}
- DEBUG=${DEBUG}
# database configuration
- PGDB_ENGINE=${PGDB_ENGINE}
- PGDB_NAME=${PGDB_NAME}
- PGDB_USER=${PGDB_USER}
- PGDB_PASSWORD=${PGDB_PASSWORD}
- PGDB_HOST=${PGDB_HOST}
- PGDB_PORT=${PGDB_PORT}
depends_on:
- postgres
restart: always

nginx:
image: nginx:stable-alpine
container_name: nginx
ports:
- "80:80"
- "443:443"
volumes:
- ./default.conf:/etc/nginx/conf.d/default.conf
- static_volume:/home/app/core/static
- media_volume:/home/app/core/media
depends_on:
- backend
restart: always

volumes:
static_volume:
media_volume:
postgres_data:


The error occurs when I run the docker-compose file, appearing at the end of the logs. Interestingly, downgrading image version to PostgreSQL 14 resolves the issue completely.

What's particularly interesting is that VS Code marks the postgres:15 Docker image as "outdated", while it doesn't show this warning for postgres:14. This seems counterintuitive since version 15 is newer.

What could be causing this protocol incompatibility between psycopg2 and PostgreSQL 15? Is there a way to resolve this while maintaining PostgreSQL 15?

Steps I've tried: Clearing all Docker volumes Rebuilding containers

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