How to Fix ModuleNotFoundError: No module named 'serial' in Python

When working with serial communication in Python, you might encounter the error ModuleNotFoundError: No module named 'serial'. This error occurs when Python can't find the PySerial module, which is essential for serial communication. Let's learn how to fix this issue.

For a more general guide about solving ModuleNotFoundError, check out our article on How To Solve ModuleNotFoundError: No module named in Python.

Understanding the Error

This error typically appears when you try to use the serial module without having it installed. The error message looks like this:

import serial

# This will raise the error if PySerial is not installed
ser = serial.Serial('/dev/ttyUSB0', 9600)

Traceback (most recent call last):
  File "your_script.py", line 1, in 
    import serial
ModuleNotFoundError: No module named 'serial'

How to Fix the Error

Solution 1: Install PySerial using pip

The simplest way to fix this error is to install the PySerial package using pip:

pip install pyserial

Solution 2: Install PySerial in a Virtual Environment

For a more isolated setup, use a virtual environment:

python -m venv myenv
source myenv/bin/activate  # On Windows: myenv\Scripts\activate
pip install pyserial

Verifying the Installation

After installation, verify that PySerial is working correctly:

import serial
print(serial.__version__)

Common Issues and Solutions

Here are some common issues you might encounter:

• Permission Errors: On Linux/Unix systems, you might need to add your user to the dialout group:

  
  sudo usermod -a -G dialout $USER
  
  

• Wrong Python Environment: Make sure you're using the correct Python interpreter where PySerial is installed.
• Package Conflicts: Try uninstalling and reinstalling PySerial if you encounter version conflicts.

Basic Usage Example

Here's a simple example of using PySerial after installation:

import serial

# Configure the serial connection
ser = serial.Serial(
    port='/dev/ttyUSB0',  # Change this to your port
    baudrate=9600,
    timeout=1
)

# Write data
ser.write(b'Hello World')

# Read data
data = ser.readline()
print(data.decode('utf-8'))

# Close the connection
ser.close()

Conclusion

The ModuleNotFoundError: No module named 'serial' is easily fixed by installing the PySerial package. Remember to use the correct Python environment and check for any permission issues if you're working with hardware serial ports.

After following these steps, you should be able to use the serial module in your Python projects for serial communication with various devices.