Common SpringBoot BeanCreationException Errors and How to Fix Them

Environment: SpringBoot 3.2.5

1. Introduction

In this article we discuss BeanCreationException , a common exception thrown by the BeanFactory when creating a defined bean fails. We explore the most common causes and solutions.

2. Exception categories

2.1 NoSuchBeanDefinitionException

This occurs when Spring tries to inject a bean that does not exist in the container, for example:

<code>public class UserDAO {}
@Service
public class UserService {
    @Resource
    private UserDAO dao;
}</code>

The UserDAO class has no annotation, causing an error when the container starts.

Check that UserDAO is annotated with @Component , @Repository , @Service , or @Controller , or defined as a @Bean , and that its package is included in component scanning.

2.2 NoUniqueBeanDefinitionException

This occurs when multiple beans of the same type exist, for example:

<code>public interface DAO {}
@Component
public class CommonDAO implements DAO {}
@Component
public class PersonDAO implements DAO {}
@Service
public class UserService {
    @Resource
    private DAO dao;
}</code>

Solution: specify the bean name with @Resource(name="personDAO") or use @Autowired together with @Qualifier :

<code>@Service
public class UserService {
    @Resource(name = "personDAO")
    private DAO dao;
}</code>

2.3 BeanInstantiationException

Occurs when an exception is thrown while creating an instance, for example:

<code>@Controller
public class UserController {
    public UserController() {
        // TODO
        throw new RuntimeException("异常了");
    }
}</code>

It also happens when an abstract class is defined as a bean:

<code>@Controller
public abstract class UserController {
    public UserController() {}
}</code>

2.4 NoSuchBeanDefinitionException (constructor)

If a bean only has a parameterized constructor and the container cannot find a matching bean for the parameter type, the exception is thrown, for example:

<code>@Component
public class User {
    public User(String name) {
        System.out.println(name);
    }
}</code>

Check that a String -type bean is defined in the container.

2.5 NotWritablePropertyException

This occurs when a property has no setter and you try to set it via BeanDefinition registration, for example:

<code>public class UserService {
    private DAO dao;
}</code>

<code>ConfigurableApplicationContext context = ...;
context.registerBean("userService", UserService.class, bd -> {
    bd.getPropertyValues().add("dao", xxx);
});</code>

Running the program results in an error.

2.6 BeanCurrentlyInCreationException

Usually caused by circular constructor injection, for example:

<code>@Component
public class A {
    public A(B b) {}
}
@Component
public class B {
    public B(A a) {}
}</code>

Solution: add @Lazy to one side of the dependency:

<code>public class A {
    public A(@Lazy B b) {}
}</code>

2.7 BeanDefinitionOverrideException

Thrown when two beans have the same name and overriding is disabled. Example:

<code>@Component("xxxooo")
public class A {}
@Component("xxxooo")
public class B {}
</code>

Configuration to disallow overriding:

<code>spring:
  main:
    allow-bean-definition-overriding: false
</code>

If overriding is enabled, the later bean replaces the earlier one.