👉 My Spring Boot App Kept Crashing… Until I Fixed Exception Handling

Everything worked perfectly during development.

APIs returned data.
Validation passed.
Features shipped.

Then an invalid request hit the system.

💥 Boom. Application crashed.

Stack traces everywhere.
Ugly error responses.
Clients confused.

That’s when I realized I had completely ignored Exception Handling.

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🧠 What is Exception Handling in Spring Boot?

Exception Handling is the process of gracefully handling errors instead of letting your application crash.

In Spring Boot MVC, proper exception handling helps you:

• Catch runtime issues
• Control API responses
• Maintain application stability

Without it, your app depends on default error behavior, which is rarely good enough.

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✅ Why Exception Handling Matters

🔹 Prevents Application Crashes

Unhandled exceptions can bring down your entire application.

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🔹 Provides User-Friendly Responses

Instead of stack traces, clients receive clear error messages.

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🔹 Improves Debugging & Maintenance

Errors are logged properly and easier to trace.

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🔹 Ensures Consistency

All APIs return errors in a uniform format, not random responses.

This is what separates demo projects from production-ready backends.

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🛠️ Ways to Handle Exceptions in Spring Boot

🔹 @ExceptionHandler

Used to handle specific exceptions inside a controller.

It allows you to:

• Catch particular exceptions
• Customize the response
• Return meaningful HTTP status codes

This works well for controller-specific logic.

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🔹 @RestControllerAdvice (Game Changer)

@RestControllerAdvice enables global exception handling.

Instead of repeating logic in every controller:

• Handle exceptions in one place
• Apply consistent responses across the application
• Keep controllers clean

Once I used this, my codebase felt instantly cleaner.

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🌐 Returning Proper HTTP Status Codes

Exception handling is not just about catching errors — it’s about responding correctly.

Good APIs:

• Return 400 for bad requests
• Return 404 for missing resources
• Return 500 for server errors

Clients rely on these status codes to behave correctly.

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📦 Custom Error Response (Highly Recommended)

Instead of returning plain strings, you can use a custom error response class.

This allows you to return:

• Error message
• Status code
• Timestamp
• Request details

Structured error responses make APIs:

• Easier to consume
• Easier to debug
• More professional

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⚠️ The Mistake I Was Making

I used to:

• Let exceptions bubble up
• Rely on default error pages
• Ignore edge cases

It worked… until real users started hitting my APIs.

Once I added proper exception handling:

• Crashes disappeared
• Error responses improved
• Debugging became easier

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🚀 Final Thoughts

Exception handling isn’t about fixing bugs.

It’s about handling failure gracefully.

If your Spring Boot APIs feel:

• Fragile
• Hard to debug
• Inconsistent

Start with Exception Handling.

This post is part of my learning-in-public journey while exploring Spring Boot and real-world backend development.

Comments

[Rajat Arora]

Excellent article!

I've been a Spring developer for over a decade, and I wish I'd found this article when I was a junior :)

Over the years I've developed some best practices for handling exceptions in Java / Spring applications:

• Handle exceptions at the lowest layer possible: You don't want an SQL exception bubbling up to the controller layer. Handle it at the Data / Repository layer itself.
• Never keep catch blocks empty: It's a BIG BIG red flag. If you took the time to wrap your code in a try, make sure that the relevant catch block actually handles the exceptional condition. Empty catch blocks are recipes for disaster in production.
• Error messages should make sense to the end user: Your end user won't care about a NullPointerException in your service layer. If an error has to be returned by your API, make sure that the exception message makes sense to a non-technical user (if your audience is non-technical, that is).
• Log every exception: The breadcrumbs left by your log messages will come in handy when you're stuck dealing with a production issue at 2AM. And yes, a production issue will happen at 2AM :)
• Never print the exception stack trace to your API response: Stack traces never make sense to the end user. Furthermore, they can leak information to malicious actors wanting to hack into your system.
• Always keep a "catch-all" exception handler in your @RestControllerAdvice: Have a method that handles @Throwable in your controller advice. This will make sure that a generic error response with a 500 status code is sent in the API response in case something untoward happens in your application that you haven't thought of beforehand.

[LANCHANA M]

Nice work

[Shashwath S H]

Thank you mam