'Access-Control-Allow-Origin' with spring boot

JUST ADD DevConfiguration in any package then update application.properties file

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
@Profile("development")
public class DevConfiguration implements WebMvcConfigurer {
 
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedMethods("GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS").allowedOrigins("*");
    }
}

Update application.properties file

# application.properties
spring.profiles.active=development
server.port=8090

Try adding this to your application:

@SpringBootApplication
@RestController
public class ChrisboltonServiceApplication {

    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurerAdapter() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                registry.addMapping("/**").allowedOrigins("*");
            }
        };
    }

...

Also, try removing the crossDomain: true from the $.ajax().