Spring Application not deploying on Heroku " ERROR: Build Failure"

Question

Heroku is a platform as a service (PaaS) that enables developers to build, run, and operate applications entirely in the cloud. I am deploying My Spring application on Heroku and it is giving a build failure error. It's working on localhost but don't know why it is not deploying, please resolve my problem. any help can be appreciated, Thanks.

Error File:

       [INFO] Changes detected - recompiling the module!
       [INFO] Compiling 25 source files to /tmp/build_d30a8927/target/classes
       [INFO] ------------------------------------------------------------------------
       [INFO] BUILD FAILURE
       [INFO] ------------------------------------------------------------------------
       [INFO] Total time:  8.201 s
       [INFO] Finished at: 2022-10-14T18:42:07Z
       [INFO] ------------------------------------------------------------------------
       [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.10.1:compile (default-compile) on project MyApp: Fatal error compiling: invalid target release: 17 -> [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
       We're sorry this build is failing! If you can't find the issue in application code,
       please submit a ticket so we can help: https://help.heroku.com/
 !     Push rejected, failed to compile Java app.
 !     Push failed

MY POM.XML

<?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>2.7.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.spring.demo</groupId>
    <artifactId>MyApp</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>MyApp</name>
    <description>Demo project for MyApp</description>
    <properties>
        <java.version>17</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-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web-services</artifactId>
        </dependency>
    
        <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>

</dependency>

<dependency>
    <groupId>org.thymeleaf.extras</groupId>
    <artifactId>thymeleaf-extras-springsecurity5</artifactId>
</dependency>
    
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>

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

</project>

Answer 1

Create a file called system.properties below the pom.xml file and write these:

java.runtime.version=17
maven.version=3.6.2

It was not working because your java version is 17 and Heroku's using default java version which is different.