Web server failed to start. Port 8080 was already in use. — how to fix

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APPLICATION FAILED TO START
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Description:

Web server failed to start. Port 8080 was already in use.

Action:

Identify and stop the process that's listening on port 8080 or configure this application to listen on another port.

Quick fix: Find and stop the process: sudo lsof -i :8080 or sudo ss -ltnp 'sport = :8080', then kill <PID> (Windows: netstat -ano | findstr :8080 then taskkill /PID <PID> /F). Or run on another port: server.port=8081 in application.properties, or --server.port=8081.

What it means

Only one process can listen on a TCP port at a time. On startup Spring Boot tries to bind its embedded web server to server.port (default 8080). The OS refused because something else holds it. Spring prints the friendly message above instead of the underlying java.net.BindException: Address already in use.

Fix 1: find and stop the process

Linux / macOS:

sudo lsof -i :8080              # shows COMMAND and PID
sudo ss -ltnp 'sport = :8080'   # Linux alternative
kill <PID>                      # then kill -9 <PID> if it ignores it

Windows (Command Prompt):

netstat -ano | findstr :8080
taskkill /PID <PID> /F

PowerShell: Get-NetTCPConnection -LocalPort 8080 | Select-Object OwningProcess.

If it's java, it's very likely an earlier run of your app.

Cause: the previous run is still alive

Common in IDEs: you click Run again instead of Restart, or close the console tab without stopping the app. In IntelliJ IDEA, open the Run/Services tool window and stop old instances; with "Allow multiple instances" unchecked (the default), Rerun replaces the old instance. Apps started with mvn spring-boot:run or ./gradlew bootRun in a terminal are stopped with Ctrl+C — Ctrl+Z only suspends them and keeps the port.

Fix 2: use a different port

src/main/resources/application.properties:

server.port=8081

or application.yml:

server:
  port: 8081

Or override at launch, without changing code:

java -jar app.jar --server.port=8081
SERVER_PORT=8081 java -jar app.jar
mvn spring-boot:run -Dspring-boot.run.arguments=--server.port=8081

server.port=0 picks a random free port (useful for tests and running several instances).

Cause: another service uses 8080

8080 is a popular default: Jenkins, Tomcat installs, other dev servers, Docker containers with -p 8080:.... Check containers:

docker ps --filter "publish=8080"

Stop that service, or move one of them to another port.

Tests

@SpringBootTest(webEnvironment = WebEnvironment.DEFINED_PORT) uses the real port and fails if the app is also running. Prefer WebEnvironment.RANDOM_PORT and inject it with @LocalServerPort.

Not a web app?

If the application shouldn't start a web server at all (batch job, CLI), disable it:

spring.main.web-application-type=none

Last updated 2026-10-31.