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Cannot resolve symbol 'SpringBootApplication'

I'm new to java springboot.. I got a new laptop and i installed all the software and started with spring.io as soon as i import im getting this error "Cannot resolve symbol 'SpringBootApplication'" i havent changed anything yet.
<?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>2.4.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>Receive</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Receive</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</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>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
Tried reimporting maven/cleared cache nothing seems to be working. Please help

Try this
File -> Invalidate Caches/Restart -> Invalidate And Restart

can you try mvn clean install -U it will force update dependencies

If that's the whole pom, you didn't close the project tag.
Add </project> below </build> and try to load maven changes to update dependencies.

Change https in this line:
https://maven.apache.org/xsd/maven-4.0.0.xsd"
to http

Maven - Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.4.1:run

I created my project at https://start.spring.io/
Several errors on the internet are similar but did not solve my problem.
when executing it I found an error return:
Failed to execute goal org.springframework.boot: spring-boot-maven-plugin: 2.4.1: run
Here are my POM and main file main
POM:
<?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>2.4.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>net.javaguides</groupId>
<artifactId>spring-boot-restfull-webservice</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring-boot-restfull-webservice</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>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>
Class:
package net.javaguides.springboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class SpringBootRestfullWebserviceApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootRestfullWebserviceApplication.class, args);
}
}
I'm new to Springboot, how do I fix it?

I've gotten your build to work, but I had to make some compromises.
I looked at the Spring documentation for what you are trying:
https://spring.io/guides/gs/rest-service/
Then I looked at the pom.xml for the example:
https://github.com/spring-guides/gs-rest-service/blob/master/complete/pom.xml
Despite the fact that the documentation says you can use Java 1.8 or higher, you need to use 1.8. If you go higher, you have to specify the property encoding in the plugin, and you can't do that because you are using the Spring Boot plugin rather than a plugin you can configure in the pom.xml for your project.
I also added a lower version of the maven-surefire-plugin than Spring Boot uses. With this version, you get the error [ERROR] There are test failures, but you are not running any tests.
I commented out the MySql and JPA dependencies, which won't work unless you have database connection settings.
<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>2.4.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>net.javaguides</groupId>
<artifactId>spring-boot-restful-webservice</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring-boot-restful-webservice</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</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>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>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.5</version>
<configuration>
<skipTests>false</skipTests>
<testFailureIgnore>true</testFailureIgnore>
<forkMode>once</forkMode>
</configuration>
</plugin>
</plugins>
</build>
</project>

In my case i was running the jar file when i was activated maven install. The made it unable to delete and create a new jar as one was already running. After i quit running the jar file. I was able to build the project. sometimes reading error messages helps

Try to read well the exception log in cli, after executing your "mvn spring-boot:run" command.
It can be a due to
a connection with your DB, for example mysql not started
Or started but the DB name is not correct in your application.properties file e.g. java.sql.SQLSyntaxErrorException: Unknown database
Or even the password used of the db user is not correct in the application.properties file: e.g Caused by: java.sql.SQLNonTransientConnectionException: Public Key Retrieval is not allowed
so analyze first your logs before modifying java version, xml elements in the plugin ...
Normally this follwing generic pom.xml is enough to have maven running successfully your tomcat server (embedded in spring boot):
<?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>2.7.2</version>
<relativePath />
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</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-web</artifactId>
</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>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>

Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.1.0.RELEASE

I don't understand the reason why I'm getting such an error in my new project, mvn spring-boot:run I get this error when I execute the command
ERROR: Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.1.0.RELEASE:run (default-cli) on project spring5webapp: An exception occurred while running. null
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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>guru.springframework</groupId>
<artifactId>spring5webapp</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>spring5webapp</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.0.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<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>com.h2database</groupId>
<artifactId>h2</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.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>

I tried with your pom.xml and it worked for me. It fails with same error only when you have same port (8080 or whatever you are using in the application) has already been occupied.
Can you please check the availability of the port on which you are trying to run.(if its occupied try running on other port or kill the same).
Also can you please paste the complete error after "null" in the stacktrace.

failed to resolve dependencies in maven multi module project

I am posting this question even though there are other questions on this. However, I did not find any solution so far on this, hence posting this question.
I am getting this error :
Could not resolve dependencies for project vehicle-tracker:vehicle-simulator:jar:0.0.1-SNAPSHOT: Failed to collect dependencies at vehicle-tracker:common-libs:jar:0.0.1-SNAPSHOT: Failed to read artifact descriptor for vehicle-tracker:common-libs:jar:0.0.1-SNAPSHOT: Could not find artifact vehicle-tracker:vehicle-tracker:pom:0.0.1-SNAPSHOT
common-libs jar is available under
.m2\repository\vehicle-tracker\common-libs\0.0.1-SNAPSHOT
The project I am trying to build is dependent over common-libs jar but maven is failed to find in local maven repo.
I am attaching following POM.xml
Parent.xml
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>vehicle-tracker</groupId>
<artifactId>vehicle-tracker</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<modules>
<module>common-libs</module>
<module>vehicle-simulator</module>
<module>tracker-dashboard</module>
</modules>
</project>
Common-libs 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>vehicle-tracker</groupId>
<artifactId>vehicle-tracker</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../vehicle-tracker</relativePath> <!-- lookup parent from repository -->
</parent>
<artifactId>common-libs</artifactId>
<name>common-libs</name>
<description>Common libraries for vehicle tracker</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
vehicle-simulator 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>vehicle-tracker</groupId>
<artifactId>vehicle-tracker</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>../../vehicle-tracker/</relativePath> <!-- lookup parent from repository -->
</parent>
<artifactId>vehicle-simulator</artifactId>
<name>vehicle-simulator</name>
<description>vehicle simulator for application</description>
<properties>
<java.version>1.8</java.version>
<swagger-version>2.9.2</swagger-version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger2</artifactId>
<version>${swagger-version}</version>
</dependency>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-swagger-ui</artifactId>
<version>${swagger-version}</version>
</dependency>
<dependency>
<artifactId>common-libs</artifactId>
<version>0.0.1-SNAPSHOT</version><!--${project.version}-->
<groupId>vehicle-tracker</groupId><!-- ${project.groupId} -->
</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 am not able to find where I am doing mistake in POM or else where ...so not able to build project vehicle-tracker.

I resolved the build error. Actually I was putting below in common-libs module's POM.xml :
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
This should be in the POM.xml of commons-lib module as it is creating spring-boot jar. Hence dependency was not available for dependent module.
After removing this block of configuration in POM.xml from commons-lib module, I am able to build the project without any issue(s).
Thank U All for looking in to this.
Just sharing this if any one having would face this knowingly or unknowingly.

How to build a multi-module Maven project without a main class in one of the modules

I've been trying to find an answer to this issue in similar questions but I still don't know what is causing it.
I have a multi-module maven project and I'm trying to run mvn install or mvn package and I get the following error
[INFO] app ................................................... SUCCESS
[ 1.025 s]
[INFO] module-data ..................................... FAILURE [
0.952 s]
[INFO] module-app ...................................... SKIPPED
[ERROR] Failed to execute goal
org.springframework.boot:spring-boot-maven-plugin:2.1.1.RELEASE:repackage
(repackage) on project project-data: Execution repackage of goal
org.springframework.boot:spring-boot-maven-plugin:2.1.1.RELEASE:repackage
failed: Unable to find main class -> [Help 1]
The project-app module has a java class in the src folder, whereas the project-data module does not have a main class.
parent 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<packaging>pom</packaging>
<modules>
<module>project-data</module>
<module>project-app</module>
</modules>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>app</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>app</name>
<description></description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</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-devtools</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</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>
project-data 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>app</artifactId>
<groupId>com.example</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>project-data</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</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>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
<configuration>
<skip>true</skip>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
project-app 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>app</artifactId>
<groupId>com.example</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>project-app</artifactId>
<dependencies>
<dependency>
<artifactId>project-data</artifactId>
<groupId>com.example</groupId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</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-devtools</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
I have something very similar to the structure of this project (sfg-pet-clinic), however, after downloading and running mvn package, it works fine. I don't see much difference between the pom files of my project and this one so what could I be missing?

Configuration is for older versions of spring.
Remove:
<configuration>
<skip>true</skip>
</configuration>
Instead, add this flag below pom artifactId
<properties>
<spring-boot.repackage.skip>true</spring-boot.repackage.skip>
</properties>
Like so:
<parent>
<artifactId>mc-pet-clinic</artifactId>
<groupId>guru.springframework</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>pet-clinic-data</artifactId>
<properties>
<spring-boot.repackage.skip>true</spring-boot.repackage.skip>
</properties>
...

I would move the entire
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
section from the parent to the module-app module, because that one is the single module which uses the repackage functionality.
Moreower I would delete the plugin section from the module-data too, because there is no need to repackage that module.

Thanks to #wemu on the comments section.
Adding this:
<configuration>
<mainClass> ${your.start.Class}</mainClass>
</configuration>
to the plugin section is required on version 2.1.1.RELEASE of the spring-boot-starter-parent dependency, as long as your class is in another module.
The project sfg-pet-clinic I referred to in my question uses an older version which does not need the <mainClass> configuration

Okay here is how I fixed that.
My Steps were:
Change the packaging of pom.xml file for project-data to pom from
jar (I used overview of Eclipse)
add <type>pom</type> in pom.xml file for project-app for dependency of module-data
<dependency>
<groupId>samee.springframework</groupId>
<artifactId>project-data</artifactId>
<version>0.0.1-SNAPSHOT</version>
<type>pom</type>
</dependency>
Then you can run your clean and package/install

I just changed the Spring Boot version in the parent pom.xml from 2.1.1 to 2.0.3 and it works.
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.3.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
Would be better to make it work in 2.1.1 though, but that's a quick and simple solution.