Heroku Springboot Err: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile

Question

I am trying to get my Springboot Backend application to compile on Heroku.

I get the message: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile

I am totally lost and in the weeds on this. Any help would be appreciated. I do not even know how or where to add the -e or -X switch (referenced below).

Here is the applicable portion of the log and my POM file.

[INFO] Downloaded from central: https://repo.maven.apache.org/maven2/com/thoughtworks/qdox/qdox/2.0-M9/qdox-2.0-M9.jar (317 kB at 10 MB/s)
       [INFO] Nothing to compile - all classes are up to date
       [INFO] 
       [INFO] --- maven-resources-plugin:3.2.0:testResources (default-testResources) @ budget-backend ---
       [INFO] Using 'UTF-8' encoding to copy filtered resources.
       [INFO] Using 'UTF-8' encoding to copy filtered properties files.
       [INFO] skip non existing resourceDirectory /tmp/build_edc50946/src/test/resources
       [INFO] 
       [INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @ budget-backend ---
       [INFO] Changes detected - recompiling the module!
       [INFO] Compiling 1 source file to /tmp/build_edc50946/target/test-classes
       [INFO] ------------------------------------------------------------------------
       [INFO] BUILD FAILURE
       [INFO] ------------------------------------------------------------------------
       [INFO] Total time:  9.635 s
       [INFO] Finished at: 2022-03-07T15:09:33Z
       [INFO] ------------------------------------------------------------------------
       [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile (default-testCompile) on project budget-backend: Fatal error compiling: invalid target release: 11 -> [Help 1]
       [ERROR] 
       [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
       [ERROR] Re-run Maven using the -X switch to enable full debug logging.
       [ERROR] 
       [ERROR] For more information about the errors and possible solutions, please read the following articles:
       [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
 !     ERROR: Failed to build app with Maven

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>net.javaguides</groupId>
    <artifactId>budget-backend</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>budget-backend</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

I added a system.properties file with 'java.runtime.version=11' and the error message from Heroku now says:

Execution repackage of goal org.springframework.boot:spring-boot-maven-plugin:2.5.0:repackage failed: Unable to find main class 

Did I make things worse or am I getting closer?

Answer 1

Problem solved. I do not understand why, but it compiles on Heroku now.

I added a system.properties file with the following entry

java.runtime.version=11.  

I also changed the POM to read

<plugins>
    <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
         <configuration>
          <skip>true</skip>
         </configuration>
         <executions>
          <execution>
           <phase>none</phase>
          </execution>
         </executions>  
    </plugin>
</plugins>