Spring Boot validation message is not being resolved

It looks like you are missing LocalValidatorFactoryBean definition in your application configuration. Below you can find an example of Application class that defines two beans: LocalValidatorFactoryBean and MessageSource that uses messages.properties file.

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.MessageSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.support.ReloadableResourceBundleMessageSource;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;

@SpringBootApplication
public class Application {

    @Bean
    public MessageSource messageSource() {
        ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
        messageSource.setBasename("classpath:messages");
        messageSource.setDefaultEncoding("UTF-8");
        return messageSource;
    }

    @Bean
    public LocalValidatorFactoryBean validator() {
        LocalValidatorFactoryBean bean = new LocalValidatorFactoryBean();
        bean.setValidationMessageSource(messageSource());
        return bean;
    }

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

Having LocalValidatorFactoryBean bean defined you can use custom validation message like:

@NotEmpty(message = "{validation.mail.notEmpty}")
@Email
private String email;

and messages.properties:

validation.mail.notEmpty=E-mail cannot be empty!

and Thymeleaf template file with:

<p th:if="${#fields.hasErrors('email')}" th:errors="*{email}">Name Error</p>

Sample application

https://github.com/wololock/stackoverflow-answers/tree/master/45692179

I have prepared sample Spring Boot application that reflects your problem. Feel free to clone it and run it locally. It will display translated validation message if value posted with form does not meet @NotEmpty and @Email validation.

WebMvcConfigurerAdapter configuration

In case of extending WebMvcConfigurerAdapter you will have to provide validator by overriding getValidator() method from parent class, e.g.:

import org.springframework.context.MessageSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ReloadableResourceBundleMessageSource;
import org.springframework.validation.Validator;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
@EnableWebMvc
public class WebConfiguration extends WebMvcConfigurerAdapter {

    @Bean
    public MessageSource messageSource() {
        ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
        messageSource.setBasename("classpath:messages");
        messageSource.setDefaultEncoding("UTF-8");
        return messageSource;
    }

    @Bean
    @Override
    public Validator getValidator() {
        LocalValidatorFactoryBean bean = new LocalValidatorFactoryBean();
        bean.setValidationMessageSource(messageSource());
        return bean;
    }

    // other methods...
}

Otherwise if you define LocalValidatorFactoryBean bean in other place it will get overridden and there will be no effect.

I hope it helps.

I am using 2.2.7 Release of Spring boot and it worked by just changing the property file name to ValidationMessages.properties and no other config required.

Not sure which version of spring boot you are using. I am using Spring boot 2.0.1.RELEASE. A clearer solution would be move all your validation messages to ValidationMessages.properties. This way you don't have to override the auto-configured Validator() and setting the MessageSource.