Understanding the “Reserved Word in URLs” Error in Python

What will you learn?

In this detailed guide, you will delve into the intricacies of encountering a “reserved word in URLs” error within your Python projects. You’ll not only unravel the solutions to rectify this issue but also gain insights into why it arises in the first place.

Introduction to the Problem and Solution

When navigating through web applications or APIs in Python, particularly while leveraging frameworks like Django or Flask, encountering an error related to using reserved words in your URL patterns is not uncommon. This hurdle may initially seem perplexing, especially for beginners in web development or those unfamiliar with such restrictions.

The crux of this dilemma lies in certain words being reserved either by the Python language itself, the web framework employed, or even within protocols like HTTP. Utilizing these reserved words as identifiers or function names can result in unexpected behavior or errors. The remedy involves understanding these reserved words, pinpointing them within your codebase, and subsequently restructuring your code to alleviate any conflicts.


# Example illustrating a problematic URL pattern that could trigger a "reserved word" error:
from my_app import views

urlpatterns = [
    path('class/', views.class_view),  # 'class' is a reserved keyword in Python.

# Copyright PHD

To resolve this issue:

# Rectified URL pattern circumventing the use of reserved keywords:
urlpatterns = [
    path('classroom/', views.class_view),  # Renamed 'class' to 'classroom'

# Copyright PHD


In the initial code snippet above, we utilized ‘class/’ as part of our URL pattern. However, class is a reserved keyword in Python designated for defining classes and cannot be employed as an identifier name. This would lead to a syntax error during execution.

By substituting ‘class/’ with something non-reserved like ‘classroom/’, we sidestep conflicts with Python’s syntax regulations while maintaining meaningful and intuitive URLs for users and developers alike. It is crucial when renaming these paths to opt for names that still clearly convey their purpose within your application’s context.

    1. What are Reserved Keywords? Reserved keywords are terms with special meanings in programming languages like Python; they cannot be used as identifiers for variables, functions, classes, etc., due to their specific purposes within the language itself.

    2. How Do I Identify Reserved Words? You can access a list of reserved keywords by importing the keyword module (import keyword) and executing keyword.kwlist.

    3. Can Frameworks Introduce Their Own Reserved Words? Absolutely! Apart from Python�s set of reserved keywords, frameworks such as Django or Flask might reserve certain words for internal usage.

    4. Is There a Standard Approach to Avoid Such Errors? A general guideline is always referring to both Python�s documentation on reserved keywords and your specific framework�s guidelines on naming conventions before assigning names to your variables or paths.

    5. Does Altering URLs Impact SEO? It could affect SEO if changes are made frequently without proper redirects. It is advisable that modifications to established URLs are accompanied by suitable HTTP redirects (e.g., 301) so search engines update their indexes correctly.

    6. What Are the Consequences of Ignoring These Errors? Neglecting errors related to reserved words can impede your application from functioning correctly�potentially leading not only technical complications but also subpar user experiences.


Addressing “reserved word in URLs” errors necessitates comprehending both programming language limitations (such as those inherent within Python) and any additional regulations imposed by utilized frameworks (like Django). By meticulously selecting identifiers that do not clash with these rules�and adjusting existing ones where needed�you ensure smoother development processes and more resilient applications.

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