I am updating a Spigot (Minecraft) plugin and the newest version of Spigot requires Java 16. In my pom I changed the maven compiler plugin target to 16 and the source is still 1.8. Now I am getting the following errors:
Failed to execute goal org.apache.maven.plugins:maven-shade-plugin:3.2.4:shade (default) on project Plugin: Error creating shaded jar: Problem shading JAR C:\Users\Trent\workspace\Stocks\Plugin\target\Plugin-1.0-SNAPSHOT.jar entry com/tchristofferson/stocks/commands/StockbrokerCommand.class: java.lang.IllegalArgumentException: Unsupported class file major version 60
pom:
<?xml version="1.0" encoding="UTF-8"?>
4.0.0
<groupId>com.tchristofferson</groupId>
<artifactId>Stocks</artifactId>
<packaging>pom</packaging>
<version>1.0-SNAPSHOT</version>
<modules>
<module>API</module>
<module>Plugin</module>
</modules>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>1.8</source>
<target>16</target>
<release>16</release>
</configuration>
</plugin>
</plugins>
</build>
<distributionManagement>
<snapshotRepository>
<id>ossrh</id>
<url>https://oss.sonatype.org/content/repositories/snapshots</url>
</snapshotRepository>
<repository>
<id>ossrh</id>
<url>https://oss.sonatype.org/service/local/staging/deploy/maven2/</url>
</repository>
</distributionManagement>
@wemu was correct that the maven shade plugin doesn't yet support Java 16. To solve the issue I had to use a snapshot version of the maven shade plugin (3.3.0-SNAPSHOT) since 3.2.4 doesn't support Java 16 yet.
I had to use this before I could use 3.3.0-SNAPSHOT
<pluginRepositories>
<pluginRepository>
<id>maven-snapshots</id>
<url>https://repository.apache.org/content/repositories/snapshots/</url>
</pluginRepository>
</pluginRepositories>
To elaborate on the answer @tchristofferson has given, I got it working by setting snapshots to true in my pluginRepository:
<pluginRepositories>
<pluginRepository>
<releases>
<updatePolicy>never</updatePolicy>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
<id>central</id>
<name>Maven Plugin Repository</name>
<url>http://repo1.maven.org/maven2</url>
</pluginRepository>
</pluginRepositories>
If you don't have the above in your pom.xml
, just add it somewhere within <project></project>
. And then change the version of the maven-shade-plugin to this:
<version>3.3.0-SNAPSHOT</version>
In my case, the latest version of maven was installed on my machine, and code was intended for the java 11 version. So I have used an older version of maven and the error didn't appear.
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