java.net.ConnectException: Connection refused
Nothing is listening at the host:port the Java client connected to.
Exact message you may see
java.net.ConnectException: Connection refused
Seen on:
Java
Meaning
Database, message broker or HTTP service not running, wrong port, or localhost used inside a container.
Common causes
- Service down
- Wrong host/port
- Docker: localhost instead of service name
- Firewall rejecting
⚡ Quick fix
- Check the target is up and listening
- Fix host/port configuration
- Use the compose service name in containers
Detailed fix by platform
Java
- Spring Boot: verify spring.datasource.url / spring.data.redis.host per environment
How to diagnose
- Target — host:port
- Service — Running?
🔧 Still not fixed?
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Last updated 13 Oct 2026