Common Issues with Port 8080
"Port 8080 is already in use"
This error occurs when another application is already using port 8080. Solutions:
- Find and close the application using port 8080
- Use a different port:
- Spring Boot:
server.port=8081 in application.properties
- Tomcat: Edit server.xml or use
-Dport=8081
- Vue.js:
vue-cli-service serve --port 8081
- On Windows, find and kill the process:
netstat -ano | findstr :8080 then taskkill /PID [PID] /F
- On Linux/Mac:
lsof -i :8080 then kill -9 [PID]
"Connection refused to localhost:8080"
If you can't connect to your application:
- Verify the application has started successfully (check logs)
- Ensure the application is binding to the correct interface (0.0.0.0 or localhost)
- Check if a firewall is blocking the connection
- Try using 127.0.0.1:8080 instead of localhost:8080
"CORS errors when connecting to localhost:8080"
If you're seeing CORS errors in your browser console:
- Configure your backend to allow CORS:
- Spring Boot: Use
@CrossOrigin or configure a CORS filter
- Tomcat: Configure a CORS filter in web.xml
- Ensure you're using the correct protocol (http vs https)
- For development, consider using a proxy in your frontend configuration