Maven Not Using Java 11: Resolving Fatal Error on Invalid Target Release

When building Java projects with Maven, encountering the error “fatal error compiling: invalid target release: 11” indicates a mismatch between the Java version specified in your project and the Java Development Kit (JDK) installed on your system. This error is significant because it can halt the build process, preventing successful compilation and deployment of your application. Ensuring compatibility between Maven and the JDK is crucial for smooth and efficient Java development workflows.

Understanding the Error

The error “Maven is not using Java 11: Fatal error compiling: invalid target release 11″ indicates that Maven is configured to compile your project with Java 11, but it can’t find the Java 11 Development Kit (JDK) on your system. Here are the common causes:

Incorrect Java Version Settings:
- Maven Configuration: Ensure your pom.xml file specifies the correct Java version:
```
<properties>
  <maven.compiler.source>11</maven.compiler.target>11</properties>
```
- JAVA_HOME Environment Variable: Make sure JAVA_HOME points to the JDK 11 installation directory.
Missing JDK 11:
- Installation: Verify JDK 11 is installed by running java -version in your terminal. If not installed, download and install it from the official Oracle website or other distributions like AdoptOpenJDK.
- Environment Variables: Set the JAVA_HOME environment variable to the JDK 11 path and update your system’s PATH variable to include JAVA_HOME/bin.
IDE Configuration:
- IDE Settings: Ensure your IDE (e.g., IntelliJ IDEA, Eclipse) is configured to use JDK 11 for both the project and Maven.

By addressing these common causes, you should be able to resolve the error and successfully compile your project with Maven using Java 11.

Verifying Java Installation

To check if Java 11 is installed and resolve the Maven error, follow these steps:

Open Terminal:
- On Windows: Open Command Prompt.
- On macOS/Linux: Open Terminal.
Check Java Version:
- Type java -version and press Enter.
- Ensure the output shows Java 11.
Set JAVA_HOME Environment Variable:
- On Windows:
  - Open System Properties > Environment Variables.
  - Add a new system variable JAVA_HOME with the path to your JDK 11 installation (e.g., C:\Program Files\Java\jdk-11).
  - Edit the Path variable and add %JAVA_HOME%\bin.
- On macOS/Linux:
  - Open your shell profile file (e.g., .bash_profile, .zshrc).
  - Add:
```
export JAVA_HOME=$(/usr/libexec/java_home -v11)
export PATH=$JAVA_HOME/bin:$PATH
```
  - Save the file and run source ~/.bash_profile or source ~/.zshrc.
Verify Maven Configuration:
- Run mvn -version to ensure Maven is using Java 11.

These steps should help you resolve the Maven error related to Java 11.

Setting JAVA_HOME Environment Variable

Here are the steps to set the JAVA_HOME environment variable to point to JDK 11 for different operating systems:

Windows

Install JDK 11: Download and install JDK 11 from the Oracle website.
Set JAVA_HOME:
- Open System Properties: Right-click on This PC > Properties > Advanced system settings.
- Click on Environment Variables.
- Under System variables, click New.
- Set Variable name to JAVA_HOME.
- Set Variable value to the JDK installation path (e.g., C:\Program Files\Java\jdk-11).
- Click OK.
Update PATH:
- In the System variables section, find and select the Path variable, then click Edit.
- Click New and add %JAVA_HOME%\bin.
- Click OK to save.

macOS

Install JDK 11: Download and install JDK 11 from the Oracle website.
Set JAVA_HOME:
- Open Terminal.
- Edit your shell profile file (e.g., ~/.bash_profile or ~/.zshrc):
```
nano ~/.bash_profile
```
- Add the following lines:
```
export JAVA_HOME=$(/usr/libexec/java_home -v 11)
export PATH=$JAVA_HOME/bin:$PATH
```
- Save the file and apply the changes:
```
source ~/.bash_profile
```

Linux

Install JDK 11: Use your package manager to install JDK 11 (e.g., sudo apt install openjdk-11-jdk for Debian-based systems).
Set JAVA_HOME:
- Open Terminal.
- Edit your shell profile file (e.g., ~/.bashrc or ~/.profile):
```
nano ~/.bashrc
```
- Add the following lines:
```
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64
export PATH=$JAVA_HOME/bin:$PATH
```
- Save the file and apply the changes:
```
source ~/.bashrc
```

Fixing Maven Error

Verify Java Installation:
```
java -version
```
Ensure it shows JDK 11.

Configure Maven to Use JDK 11:

Edit your pom.xml file to specify the Java version:

<properties>
  <maven.compiler.source>11</maven.compiler.source>
  <maven.compiler.target>11</maven.compiler.target>
</properties>

Verify Maven Configuration:
```
mvn -version
```
Ensure it shows JDK 11.

These steps should help you resolve the “Maven is not using Java 11” error.

Configuring Maven to Use JDK 11

Open your pom.xml file.

Add the following properties to specify the Java version:

<properties>
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
</properties>

Configure the Maven Compiler Plugin:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <source>11</source>
                <target>11</target>
            </configuration>
        </plugin>
    </plugins>
</build>

These steps should resolve the “maven is not using java 11 fatal error compiling invalid target release 11” issue.

Verifying Maven Configuration

Verify JDK 11 Installation:
```
java -version
```

Set JAVA_HOME Environment Variable:

Windows:

setx JAVA_HOME "C:\Program Files\Java\jdk-11"
setx PATH "%JAVA_HOME%\bin;%PATH%"

macOS/Linux:

export JAVA_HOME=$(/usr/libexec/java_home -v 11)
export PATH=$JAVA_HOME/bin:$PATH

Configure Maven to Use JDK 11:
Add to pom.xml:

<properties>
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
</properties>

Verify Maven Configuration:
```
mvn -version
```