UnsatisfiedDependencyException: Error creating bean with name

UnsatisfiedDependencyException is a runtime exception that is thrown when the Spring framework is unable to resolve a dependency for a bean. It usually indicates that a required bean is not found in the application context, or that a required bean is not configured properly.

This exception can occur at runtime when you are trying to create a bean instance using the Spring framework's dependency injection feature. It can have various causes, such as:

• A required dependency is not defined in the application context.
• A required dependency is defined, but it is not of the expected type.
• A required dependency is defined, but it has not been initialized properly.

Example

Consider a service that depends on another component:

@Component
public class OrderService {
    @Autowired
    private PaymentService paymentService;
}

If PaymentService is missing from the classpath or lacks a Spring stereotype annotation, Spring will throw UnsatisfiedDependencyException during startup. Adding the missing annotation or ensuring the package is included in component scanning resolves the issue.

Troubleshooting

To troubleshoot this exception, you can try the following:

• Make sure that all required dependencies are defined in the application context by verifying they have a Spring stereotype annotation (e.g., @Component, @Service) and reside in a package scanned by @SpringBootApplication or @ComponentScan.
• Check the types of the dependencies to make sure they match the expected types. If multiple beans of the same type exist, use @Qualifier to specify the exact bean name.
• Check the initialization of the dependencies to make sure they are properly configured. Ensure that required properties or environment variables are present in your application.properties or application.yml.

It might also be helpful to enable debug logging for the Spring framework by adding logging.level.org.springframework=DEBUG to your configuration file. This can provide more information about the cause of the exception.