Spring Boot Troubleshooting

Introduction Duplicate requests are one of the most damaging bugs in production REST APIs — a user double-clicks “Pay Now,” a mobile client retries after a network blip, or a load balancer resends a request that never got acknowledged. Without protection, this can mean double-charged customers, duplicate orders, or duplicate emails sent. What makes this […]

A response timeout happens when a client (browser, mobile app, another microservice, or a load balancer) gives up waiting for your Spring Boot API to finish responding. Unlike a request timeout (client failing to send data in time), a response timeout means the server accepted the request but couldn’t finish processing and writing the response

Introduction One of the most common errors developers encounter while building REST APIs is the HTTP 404 Endpoint Not Found response. Unlike an HTTP 500 Internal Server Error, which indicates a server-side failure, a 404 means the requested resource or endpoint could not be located. Although a 404 appears straightforward, identifying the root cause can

Introduction A request timeout is one of the most frustrating production issues in Spring Boot applications. Users click a button, wait for several seconds, and eventually receive an error instead of the expected response. Unlike an HTTP 500 Internal Server Error, where the application fails immediately, a timeout indicates that the server did not complete

Global exception handling is one of the most important features in any Spring Boot REST API. Instead of returning stack traces or inconsistent error responses, it allows you to handle exceptions in one central location using @ControllerAdvice and @ExceptionHandler. However, many developers encounter situations where global exception handling simply doesn’t work. Common symptoms include: This

One of Spring Boot’s most powerful features is Auto-Configuration. It eliminates the need to manually configure common components like data sources, embedded servers, security, and JPA. However, this convenience can also become confusing. Developers often encounter situations where Spring Boot creates beans they didn’t expect, fails to configure components automatically, or behaves differently between development

Seeing a NullPointerException even though you’ve used @Autowired is one of the most common and frustrating problems for Spring Boot developers. It often leads developers to believe that Spring has failed to inject a dependency, when the actual issue lies in how the object was created or configured. In most cases, the problem is not

Bean creation failures are one of the most common reasons Spring Boot applications fail to start in production.In many real-world cases, the root cause is circular dependency, misconfigured beans, or unexpected proxy behavior. This guide explains why bean creation fails, how circular dependencies actually happen, and how to fix them permanently in production-grade Spring Boot

One of the most common issues developers encounter when using Spring Boot with JPA is: “Tables are not being created automatically by Hibernate.” You expect Hibernate to generate tables based on your entities —but nothing happens. In this production-grade guide, you will learn: This post is written for beginners, intermediate developers, and architects building real

One of the most common and frustrating errors when starting a Spring Boot application is: “Failed to configure a DataSource” This often happens when a Spring Boot app tries to connect to a database during startup, but cannot create a proper DataSource.In production systems and real projects, this error points to misconfiguration, missing dependencies, or