Erro ao acessar o banco H2

Oi Jonata,

Verifica no console do Eclipse se ocorreu alguma exception e posta ela aqui. Aproveita e coloca aqui também suas configurações e códigos.

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.4.RELEASE)

2021-05-30 20:13:10.535  INFO 5808 --- [  restartedMain] br.com.alura.forum.ForumApplication      : Starting ForumApplication on DESKTOP-RA8U7TQ with PID 5808 (C:\eclipse\workspace\forum\target\classes started by Windows in C:\eclipse\workspace\forum)
2021-05-30 20:13:10.537  INFO 5808 --- [  restartedMain] br.com.alura.forum.ForumApplication      : No active profile set, falling back to default profiles: default
2021-05-30 20:13:10.566  INFO 5808 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2021-05-30 20:13:10.566  INFO 5808 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2021-05-30 20:13:11.097  INFO 5808 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data repositories in DEFAULT mode.
2021-05-30 20:13:11.153  INFO 5808 --- [  restartedMain] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 50ms. Found 2 repository interfaces.
2021-05-30 20:13:11.398  INFO 5808 --- [  restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration' of type [org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration$$EnhancerBySpringCGLIB$$f478fd7b] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2021-05-30 20:13:11.744  INFO 5808 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2021-05-30 20:13:11.763  INFO 5808 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-05-30 20:13:11.763  INFO 5808 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.17]
2021-05-30 20:13:11.867  INFO 5808 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2021-05-30 20:13:11.867  INFO 5808 --- [  restartedMain] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1301 ms
2021-05-30 20:13:11.982  INFO 5808 --- [  restartedMain] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2021-05-30 20:13:12.122  INFO 5808 --- [  restartedMain] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
2021-05-30 20:13:12.160  INFO 5808 --- [  restartedMain] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [
    name: default
    ...]
2021-05-30 20:13:12.213  INFO 5808 --- [  restartedMain] org.hibernate.Version                    : HHH000412: Hibernate Core {5.3.9.Final}
2021-05-30 20:13:12.214  INFO 5808 --- [  restartedMain] org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found
2021-05-30 20:13:12.320  INFO 5808 --- [  restartedMain] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.4.Final}
2021-05-30 20:13:12.433  INFO 5808 --- [  restartedMain] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.H2Dialect
2021-05-30 20:13:13.013  INFO 5808 --- [  restartedMain] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2021-05-30 20:13:13.042  INFO 5808 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2021-05-30 20:13:13.400  INFO 5808 --- [  restartedMain] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2021-05-30 20:13:13.441  WARN 5808 --- [  restartedMain] aWebConfiguration$JpaWebMvcConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
2021-05-30 20:13:13.604  INFO 5808 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2021-05-30 20:13:13.606  INFO 5808 --- [  restartedMain] br.com.alura.forum.ForumApplication      : Started ForumApplication in 3.263 seconds (JVM running for 3.871)

# data source
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.url=jdbc:h2:mem:alura-forum
spring.datasource.username=sa
spring.datasource.password=

# jpa
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.hibernate.ddl-auto=update
spring.jpa.defer-datasource-initialization=true

# h2
spring.h2.console.enabled=true
spring.h2.console.path=/h2-console

<?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>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>br.com.alura</groupId>
    <artifactId>forum</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>forum</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-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</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-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
    </dependencies>

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

</project>

package br.com.alura.forum.controller;

import java.net.URI;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.util.UriComponentsBuilder;

import br.com.alura.forum.controller.dto.TopicoDto;
import br.com.alura.forum.controller.form.TopicoForm;
import br.com.alura.forum.modelo.Topico;
import br.com.alura.forum.repository.CursoRepository;
import br.com.alura.forum.repository.TopicoRepository;

@RestController
@RequestMapping("/topicos")
public class TopicosController {

    @Autowired
    private TopicoRepository topicoRepository;
    @Autowired
    private CursoRepository cursoRepository;

    @GetMapping
    public List<TopicoDto> lista(String nomeCurso) {
        if (nomeCurso == null) {
            List<Topico> topicos = topicoRepository.findAll();
            return TopicoDto.converter(topicos);
        } else {
            List<Topico> topicos = topicoRepository.findByCursoNome(nomeCurso);
            return TopicoDto.converter(topicos);

        }
    }

    @PostMapping
    public ResponseEntity<TopicoDto> cadastrar(@RequestBody TopicoForm form, UriComponentsBuilder uriBuilder) {
        Topico topico = form.converter(cursoRepository);
        topicoRepository.save(topico);
        URI uri = uriBuilder.path("/topicos/{id}").buildAndExpand(topico.getId()).toUri();
        return ResponseEntity.created(uri).body(new TopicoDto(topico));
    }
}

Se precisar de mais alguma informação, pode pedir professor....

Blz!

E o erro acontece quando você dispara qual requisição?

Olá professor, Revisei a aula que você fez... acabei errando o nome da url... por esse motivo não estava funcionando... Erro de iniciante...kkkk Mas obrigado pela atenção e prontidão em nos ajudar. O curso está muito bom, parabéns.