Spring Boot’s dependency injection is one of the framework's most powerful features, enabling developers to wire components seamlessly. However, encountering UnsatisfiedDependencyException can disrupt your application’s lifecycle and lead to confusion. In this article, we will dissect the reasons behind this exception and demonstrate step-by-step methods to resolve it, supplemented with detailed code examples and explanations. If you’ve ever been puzzled by this error, you’re not alone—and this guide will show you how to overcome it effectively.