Java & Python Debugging Guides

Step-by-step fixes for NullPointerException, Python tracebacks, Spring Boot errors, and more

RSS Feed
Java

spring transactional not working fix

You added @Transactional to your method, but the transaction isn't rolling back or isn't applying at all. Here's what's really happening.

Java Spring Spring Boot Transactions
Python

flask circular import error fix

You split your Flask app into multiple files and suddenly ImportError strikes. Circular imports are the culprit — here's how to fix them.

Python Flask ImportError WebDev
Java

spring jackson serialization error fix

Your Spring REST endpoint works fine until it tries to return data — then boom, a 500 with 'No serializer found for class'. Here's how to diagnose and fix it.

Java Spring Jackson WebDev
Java

spring boot autowired null fix

Your @Autowired field is null when it shouldn't be? Here's why Spring isn't injecting your dependencies.

Java Spring Spring Boot Dependency Injection
Java

spring boot nosuchbeandefinition error fix

Spring can't find your bean? NoSuchBeanDefinitionException means the bean you're trying to inject doesn't exist in the application context.

Java Spring Spring Boot Debugging
Java

spring jpa lazyinitializationexception fix

Getting 'failed to lazily initialize a collection' errors? You're trying to access data after the Hibernate session closed.

Java Spring JPA Hibernate
Python

Python KeyError: How to Fix Dictionary Key Errors

Seeing 'KeyError' in your Python code? Learn how to handle missing dictionary keys with practical examples and proven techniques.

Python KeyError Debugging Error Handling Dictionary
Java

Fix StackOverflowError: Java Complete Guide

Getting StackOverflowError? Learn what causes it, how to debug it, and how to fix it for good. Covers recursion issues, circular references, and practical solutions.

Java StackOverflowError Recursion Debugging
LLM

Toon Format: A New JSON-Compatible Data Format for LLMs

JSON is great for APIs, but it's token-heavy for LLMs. Meet Toon Format (TOON)—a schema-aware, token-efficient alternative that could save you 40% on token costs.

LLM Data Format JSON Optimization Toon
Python

Python TypeError: How to fix the 'NoneType'

Is your Python code blowing up with 'NoneType' object is not subscriptable? Here is a quick guide to fixing the most common TypeErrors in Python.

Python TypeError Debugging Error Handling
Java

Solving ConcurrentModificationException in Java

Blowing up your loops with ConcurrentModificationException? Here is the lowdown on why it happens and the right way to modify collections while iterating.

Java ConcurrentModificationException Collections Debugging
Python

Fix AttributeError in Python: Complete Guide

Seeing 'AttributeError: object has no attribute'? Learn how to fix it fast with practical examples and proven debugging techniques.

Python AttributeError Debugging Error Handling
Java

Fix NoSuchElementException: Java Iterator Guide

The complete guide to understanding, debugging, and preventing NoSuchElementException in Java. From iterator patterns to Optional handling with practical examples.

Java NoSuchElementException Iterator Exception Handling
Java

Debug IllegalArgumentException Stack Traces Fast

Learn how to debug IllegalArgumentException efficiently using Debugly's stack trace formatter. Get clear, formatted traces for common Java parameter validation errors.

Java IllegalArgumentException Stack Trace Debugly
Java

IllegalArgumentException: 5 Ways to Fix It

Master the critical java.lang.IllegalArgumentException with our comprehensive guide. Learn what causes parameter validation failures, how to debug them effectively.

Java IllegalArgumentException Input Validation Exception Handling
Java

ClassCastException Fixed: Master Type Casting Error

Master ClassCastException handling with comprehensive coverage of type casting, generics, instanceof checks, and modern Java solutions.

Java ClassCastException Type Safety Exception Handling
Java

Fix ArrayIndexOutOfBounds: Complete Solution

Guide to fixing ArrayIndexOutOfBoundsException in Java. From array indexing basics to advanced prevention strategies with practical examples.

Java ArrayIndexOutOfBoundsException Exception Handling Debugging
Java

Fix NullPointerException: Java NPE Guide

Master the dreaded java.lang.NullPointerException with our comprehensive guide. Learn what causes NPE, how to debug it effectively.

Java NullPointerException Exception Handling Debugging
Java

15+ Java Exceptions Every Developer Must Know [2025]

From NullPointerException to custom exceptions - understand every Java exception you'll encounter. Includes practical examples and debugging strategies.

Java Exception Handling RuntimeException Best Practices