We had an issue with a SpringBoot web app where we had the following error message when querying /manage/beans

Could not write JSON Attempted to serialize java.lang.Class Forgot to register a type adapter?

This was due to org.springframework.boot.actuate.beans.BeansEndpoint.BeanDescriptor having a java.lang.Class<?> attribute.

We fixed it by configuring our Gson bean this way :

    @Bean
    public static Gson gson() {
        return new GsonBuilder()
                ...
                .addSerializationExclusionStrategy(new ExclusionStrategy() {
                    @Override
                    public boolean shouldSkipField(FieldAttributes field) {
                        return field.getDeclaredType().getTypeName().equals("java.lang.Class<?>");
                    }
                    @Override
                    public boolean shouldSkipClass(Class<?> clazz) {
                        return false;
                    }
                })
                .create();
    }

Simply add the following class to your project. It will be automatically registered at start-up if you use the @EnableAutoConfiguration annotation :

@ControllerAdvice  // Makes this the default behaviour of all controllers
@ConditionalOnProperty(prefix = "app", name = "disable-default-exception-handling")
class GlobalControllerExceptionHandler {
    @ExceptionHandler(Exception.class)  // Catch any exception
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)  // Returns an error code …

I've lost quite some time on this error recently :

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is java.lang.AbstractMethodError: org.hibernate.jpa.boot …