“Debugging 101: How to Read and Understand Python Error Messages”



This content originally appeared on DEV Community and was authored by Mithu_kr

We’ve all been there — you run your code confidently, only to see a red wall of error messages screaming back at you.

But here’s the secret 👉 those errors aren’t your enemies — they’re your teachers.

In this article, we’ll decode 5 of the most common errors, understand what they mean, why they happen, and how to fix them — so next time you debug, you do it like a pro 🔍

1⃣ Undefined Variable Error

🧩 What It Means

Your code tries to use a variable before it has been defined.

💥 Example

print(name)  # 'name' is not defined

💀 Error Message

NameError: name 'name' is not defined

✅ Fix

name = "Rohan"
print(name)

🧰 Debug Tip

Use print() to check variables:

print(locals())

2⃣ Syntax Error

🧩 What It Means

Your code breaks Python’s grammar rules — missing colons, wrong indentation, etc.

💥 Example

def greet()
    print("Hello")

💀 Error Message

SyntaxError: expected ':'

✅ Fix

def greet():
    print("Hello")

🧰 Debug Tip

Use an IDE or linter (like flake8 or black) — it catches syntax issues early.

3⃣ Type Error

🧩 What It Means

You’re trying to mix incompatible data types.

💥 Example

x = "5" + 3

💀 Error Message

TypeError: can only concatenate str (not "int") to str

✅ Fix

x = int("5") + 3
print(x)

🧰 Debug Tip

Print the data type before operations:

print(type(x))

4⃣ Network Error

🧩 What It Means

Your program failed to connect to an external server or API.

💥 Example

import requests

response = requests.get("https://invalid-url-example.com")
print(response.text)

💀 Error Message

requests.exceptions.ConnectionError: Failed to establish a new connection

✅ Fix

try:
    response = requests.get("https://api.github.com/users/octocat")
    print(response.json())
except requests.exceptions.RequestException as e:
    print("Network Error:", e)

🧰 Debug Tip

  • Check your internet or URL spelling
  • Use ping or curl to test manually
  • Add timeout=5 to avoid hanging requests

5⃣ Infinite Loop Error

🧩 What It Means

Your loop condition never becomes false — your program runs forever 😅.

💥 Example

count = 0
while count < 5:
    print(count)
    # forgot to increment count

💀 Result

This loop never ends, flooding your console.

✅ Fix

count = 0
while count < 5:
    print(count)
    count += 1

💡 Final Thoughts

Error messages can look scary at first, but once you learn to read them like clues, debugging becomes an adventure, not frustration.

The next time your code throws an error — don’t panic.
Take a breath, read carefully, and debug with intention.

🧑‍💻 If this article helped you, drop a ❤ and follow me for more bite-sized debugging lessons every week!

python #debugging #webdev #beginners


This content originally appeared on DEV Community and was authored by Mithu_kr