Fix Python RecursionError: maximum recursion depth exceeded (2025 Guide)

Posted on: March 22, 2025

Encountered a "RecursionError: maximum recursion depth exceeded" in Python? This error occurs when a recursive function calls itself too many times, exceeding Python’s default recursion limit. Let’s fix it fast in this 2025 guide!

What Causes "RecursionError: maximum recursion depth exceeded"?

This error happens when Python’s recursion stack overflows due to excessive recursive calls. Python sets a default limit (usually 1000) to prevent infinite recursion. Common causes include:

• Infinite Recursion: A recursive function lacks a proper base case to stop.
• Deep Recursion: The problem requires more recursive calls than the default limit allows.
• Unintentional Loops: Logic errors causing unintended recursive calls.

Check this demo (run in a Python environment):

# This will trigger "RecursionError"
def infinite():
    infinite()  # No base case
infinite()

Running this throws a RecursionError because `infinite()` keeps calling itself endlessly.

How to Fix It: 3 Solutions

Let’s resolve this error with practical steps:

(Diagram: Developer runs recursive function, gets error, adds base case or adjusts limit, runs successfully.)

Solution 1: Add a Base Case

Ensure your recursive function has a condition to stop:

# Wrong
def infinite():
    infinite()

# Fixed
def factorial(n):
    if n <= 1:  # Base case
        return 1
    return n * factorial(n - 1)
print(factorial(5))  # 120

Add a base case to halt recursion when the condition is met.

Solution 2: Increase Recursion Limit

Adjust Python’s recursion limit for deep but valid recursion:

# Wrong (exceeds default limit)
def deep(n):
    if n <= 0:
        return 0
    return deep(n - 1) + 1
print(deep(1500))

# Fixed
import sys
sys.setrecursionlimit(2000)  # Increase limit
def deep(n):
    if n <= 0:
        return 0
    return deep(n - 1) + 1
print(deep(1500))  # 1500

Use `sys.setrecursionlimit()` cautiously—too high a value risks stack overflow crashes.

Solution 3: Use Iteration Instead

Replace recursion with a loop for efficiency:

# Wrong (recursive)
def factorial(n):
    if n <= 1:
        return 1
    return n * factorial(n - 1)

# Fixed (iterative)
def factorial_iter(n):
    result = 1
    for i in range(1, n + 1):
        result *= i
    return result
print(factorial_iter(5))  # 120

Loops avoid recursion limits entirely and often perform better.

Quick Checklist

• No base case? (Add one to stop recursion)
• Deep recursion needed? (Increase limit with caution)
• Performance matters? (Switch to iteration)

Conclusion

The "RecursionError: maximum recursion depth exceeded" in Python is a sign your recursive logic needs tweaking. With these 2025 solutions, you can tame recursion and keep your code running smoothly. Got another Python error? Let us know in the comments!