Fixing Modulenotfounderror No Module Named cython

Fixing Modulenotfounderror: No Module Named ‘cython’

The “modulenotfounderror: no module named ‘cython'” is one of the most common errors that Python programmers encounter. This error message is raised by Python when it cannot find the module “cython” in the program. In this blog post, we will explore the significance of this error message and its impact on Python programming. We will also define the key terms in the title, including modulenotfounderror and cython. Furthermore, we will provide an overview of the importance of the Cython library in Python programming, which is relevant to understanding this error message.

Problem Diagnosis

If you encountered the modulenotfounderror and received a message that no module named ‘cython’ was found, there are several potential causes for this error. One possible scenario is that the Cython package was not installed properly, which can be resolved by running pip install Cython. Another common issue is installing the package on a different version of Python than the one currently being used, or installing it globally rather than in the virtual environment. Naming your module can also lead to errors as it may shadow the official module. Additionally, incorrect versions of Python may be run by your IDE, leading to issues with module loading. Confusion with other similar errors such as “import error” or “no module named” should also be considered.

Solution to modulenotfounderror: cython not found

The ModuleNotFoundError may arise when the cython module cannot be found due to various reasons. The most common reasons are not having the Cython package installed, installing the package in the wrong Python version, or installing the package globally instead of the virtual environment. Also, naming your module “” would shadow the official module.

To resolve this error, open File>Settings>Project from the PyCharm menu. Then, select your current project, and click the Python Interpreter tab within your project tab. Click the small + symbol to add a new library to the project. Now, type in the library to be installed – cython, without quotes – and click Install Package. Wait for the installation to terminate and close all pop-ups. This solution works every time, and the above steps provide a step-by-step guide on how to install the cython library using pip or Anaconda.

Alternative Solutions to Modulenotfounderror

Modulenotfounderror may still occur even after installing Cython, but here are alternative solutions to fix this error:

Fixing the Python Interpreter Path

If the Cython fix does not work, you can try fixing the path of the Python interpreter. This solution tackles the issue of having multiple versions of Python in your system. To fix this, you can set the path of your Python interpreter to the version of Python you are using in your current project.

Using Virtual Environments

Another solution is to use virtual environments, which creates an isolated environment for your project. This allows you to install different versions of packages and avoid conflicts with other projects. You can create a virtual environment using the command python3 -m venv env and activate it using source env/bin/activate.

Installing Python from Scratch

If all else fails, you can try installing Python from scratch. This solution ensures that there are no conflicting packages or versions in your system. You can download the latest version of Python from the official website and follow the installation steps.

Understanding the “import” statement

When writing code in Python, you may need to use pre-existing code in the form of modules. The “import” statement is used to bring in these modules so that their functionality can be used in your program. When Python encounters an “import” statement, it searches for the module in the following order:

  • The built-in modules that come with Python
  • The directories specified in the PYTHONPATH environment variable (if set)
  • The installation-dependent default path

It is important to note that once you have imported a module, it is only available in that module’s namespace, and not in the global namespace, unless you explicitly import it there as well. Therefore, it is recommended to use absolute imports when importing modules to avoid naming conflicts and improve readability.

Clarifying Error Messages: ImportError vs ModuleNotFoundError

When working with Python, it’s not uncommon to encounter errors related to missing modules. Two of the most common errors are ImportError and ModuleNotFoundError. Although they may seem interchangeable, there are some subtle differences between these two error messages.

The ImportError occurs when Python cannot load a particular module, often due to an issue with the module’s installation or import location. On the other hand, ModuleNotFoundError is raised when Python is unable to find a specified module in the module search path.

It is vital to understand the differences between these errors to quickly identify and fix the problem. An ImportError may result from installing a package in the wrong Python version, while a ModuleNotFoundError can occur due to not installing the required package at all or installing it globally instead of in a virtual environment. Additionally, naming a module or shadowing the official module can result in this error message.

When troubleshooting an error, or when writing and testing Python code, it is useful to know which error message you are likely to get. By knowing the differences between ImportError and ModuleNotFoundError, you can make better decisions as to how you should proceed in fixing the error.


Q: How do I check if cython is installed?

A: A simple way to check if cython library is installed is by opening the Python shell and typing “import cython”. If no error message is displayed, then the cython library is installed.

Q: What should I do if I still get modulenotfounderror even after installing cython?

A: It is possible that the PATH environment variable is not correctly set up. Try adding the Cython installation path to the PATH environment variable.


In conclusion, the “ModuleNotFoundError: No module named ‘cython'” error message can be caused by various reasons, such as poor module installation or using an incorrect Python version. It is important to understand the root cause of the error and how to identify it properly to effectively resolve the issue. Proper installation practices are crucial for optimal performance and stability. With this knowledge, developers can ensure that their programs run smoothly and effectively import required modules.


Cython official website

Python documentation on importing modules

RealPython article on pip

Being a web developer, writer, and blogger for five years, Jade has a keen interest in writing about programming, coding, and web development.
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