Troubleshooting

The Troubleshooting category collects reproducible fixes for common developer errors. It focuses on Python, JavaScript, Java, Git, Docker, GitHub Actions, and Jekyll issues with cause, quick fix, commands, and verification steps.

If you arrived from an exact error message, match the tool, version, and operating system first, then run the verification step before moving on.

Start Here

Latest Articles

Fix GitHub Pages Jekyll Build Failed

6 minute read

Fix GitHub Pages Jekyll build failed errors by checking Pages workflow logs, _config.yml YAML, front matter dates, includes, plugins, Sass, and local Jekyll ...

How to Fix GitHub Actions Build Failed

6 minute read

Fix GitHub Actions build failed errors by reading the failed step log, checking workflow YAML, dependency install commands, runner versions, secrets, and bra...

Fix Property Does Not Exist on Type

5 minute read

Fix TypeScript Property does not exist on type errors by correcting object types, API response types, union narrowing, nullable DOM values, and unsafe any ca...

Fix TypeScript Cannot Find Name

6 minute read

Fix TS2304 Cannot find name in TypeScript by checking imports, type packages, tsconfig lib and types settings, globals, and the correct project config.

Fix Cannot Find Module in Node.js

6 minute read

Fix Node.js Cannot find module errors by checking missing packages, relative paths, working directory, CommonJS and ESM syntax, and package export paths.

How to Fix npm ERR ERESOLVE

5 minute read

Fix npm ERR ERESOLVE by identifying the peer dependency conflict, aligning package versions, refreshing the lockfile, and using legacy-peer-deps only when ne...

Python venv Not Activating: How to Fix It

5 minute read

Fix Python venv activation problems by using the right shell command, checking PowerShell policy, and verifying the active interpreter path.

How to Fix No module named pip in Python

5 minute read

Fix Python’s No module named pip error by installing pip with ensurepip, checking the active interpreter, and repairing virtual environments.

How to Fix pip install Failed in Python

6 minute read

Fix pip install failed errors by checking the active Python environment, upgrading pip, using a virtual environment, and reading the exact install error.

How to Automate Tasks with Git Hooks

3 minute read

Discover how to use Git hooks to trigger custom scripts at specific points in the Git workflow, such as before a commit or after a push.

How to Handle KeyboardInterrupt in Python

3 minute read

In Python, KeyboardInterrupt is an exception raised when the user presses Ctrl+C to forcefully terminate a program. Handling this exception correctly allows ...

How to Fix Python FloatingPointError

3 minute read

In Python, a FloatingPointError occurs when a floating-point operation fails. This error is not common but can appear in specific mathematical calculations. ...

Processing Data with Java Stream API

4 minute read

Discover the power of the Java Stream API for processing collections of data. Learn how to use streams to write declarative, efficient, and readable code for...

Using Generics in Java for Type Safety

4 minute read

Discover how Java Generics work, how they provide type safety at compile time, and how to use them to create flexible and reusable code with collections and ...

Understanding equals() and hashCode() in Java

4 minute read

Learn why you must always override hashCode() if you override equals() in Java. Understand the contract between these two methods and how they work with hash...

Java Exceptions: Checked vs. Unchecked

4 minute read

Learn the difference between checked and unchecked exceptions in Java, when to use them, and how they impact your code’s design and robustness.

How to Revert a Commit in Git (git revert)

4 minute read

Sometimes you need to safely undo the changes from a specific commit in Git. ‘git revert’ solves this by creating a new commit that undoes the changes withou...

How to Fix “MemoryError” in Python

3 minute read

In Python, a MemoryError occurs when the program exhausts the available system memory. This article explains the causes of MemoryError and how to fix it.

How to Fix “this is undefined” in JavaScript

3 minute read

In JavaScript, ‘this’ is dynamically determined by the calling context. This often leads to issues where ‘this’ becomes undefined in callback functions or ev...

How to Fix JavaScript Event Listener Leaks

4 minute read

Failing to remove event listeners can cause memory leaks and degrade application performance. This article explains the causes of event listener leaks in Jav...

How to Fix “Error: ‘;’ expected” in Java

3 minute read

In Java, “’;’ expected” is a basic compilation error that occurs when a semicolon is missing at the end of a statement. This article explains the cause of th...

How to Fix Git “Detached HEAD” State

4 minute read

Understand what a “Detached HEAD” state in Git is, why it happens, and how to safely get back to a branch without losing your work.

How to Fix Java’s StackOverflowError

5 minute read

Understand and resolve Java’s StackOverflowError by identifying infinite recursion in your code. Learn how to debug recursive functions, refactor them into i...

How to Handle java.sql.SQLException in Java

4 minute read

Learn to handle java.sql.SQLException by properly managing database connections, statements, and using try-catch-finally blocks to ensure resources are closed.

How to Fix Java’s OutOfMemoryError

5 minute read

Understand and resolve Java’s OutOfMemoryError by identifying its causes, such as memory leaks or insufficient heap size. Learn how to analyze heap dumps and...

How to Handle NumberFormatException in Java

4 minute read

Learn to prevent and handle Java’s NumberFormatException by validating strings before parsing and using try-catch blocks for safe numeric conversion.

How to Fix Java’s NoClassDefFoundError

4 minute read

Resolve Java’s NoClassDefFoundError by understanding its cause: a class that was present at compile time is missing at runtime. Learn to check your classpath...

How to Fix Java’s IllegalStateException

4 minute read

Understand and resolve Java’s IllegalStateException by ensuring methods are called only when an object is in the appropriate state. Learn through practical e...

How to Handle IllegalArgumentException in Java

5 minute read

Learn to use and handle Java’s IllegalArgumentException effectively by performing explicit checks at the beginning of your methods to ensure arguments are va...

How to Fix ModuleNotFoundError in Python

4 minute read

A guide to resolving the ModuleNotFoundError: No module named ‘…’ in Python. Learn how to install and manage modules to avoid this common error.

How to Fix Python’s KeyError: ‘…’

3 minute read

Learn how to fix the Python KeyError, which occurs when you try to access a key that does not exist in a dictionary. This guide covers several effective meth...

How to Fix FileNotFoundError in Python

3 minute read

A detailed guide on how to handle the FileNotFoundError: [Errno 2] No such file or directory in Python. Learn the common causes and effective solutions.