Langchain: ModuleNotFoundError: No module named 'langchain'

Question

When I write code in VS Code, beginning with:

import os
from langchain.chains import RetrievalQA
from langchain.llms import OpenAI
from langchain.document_loaders import TextLoader

I am met with the error: ModuleNotFoundError: No module named 'langchain'

I have updated my Python to version 3.11.4, have updated pip, and reinstalled langchain. I have also checked sys.path and the folder C:\\Python311\\Lib\\site-packages in which the Langchain folder is, is appended.

EDIT: Langchain import works when I run it in the Python console (functionality works too), but when I run the code from the VSCode run button it still provides the ModuleNotFoundError.

Has anyone else run into this issue and found a solution?

Ambulatory

Answer 1

I had installed packages with python 3.9.7 but this version was causing issues so I switched to Python 3.10. When I installed the langhcain it was in python 3.9.7 directory. If yo run pip show langchain, you get this

Name: langchain
Version: 0.0.220
Summary: Building applications with LLMs through composability
Home-page: https://www.github.com/hwchase17/langchain
Author: 
Author-email: 
License: MIT
Location: /home/anaconda3/lib/python3.9/site-packages
Requires: aiohttp, async-timeout, dataclasses-json, langchainplus-sdk, numexpr, numpy, openapi-schema-pydantic, pydantic, PyYAML, requests, SQLAlchemy, tenacity
Required-by: jupyter_ai, jupyter_ai_magics

If you look at the Location property, you see this /home/anaconda3/lib/python3.9/site-packages. But since I am using Pyhton3.10 I had to make sure langchain is in the directory of Python 3.10. so installed the langhchain with

python3.10 -m pip install langchain   

now when I run, python3.10 -m pip show langchain I get this

Name: langchain
Version: 0.0.264
Summary: Building applications with LLMs through composability
Home-page: https://www.github.com/hwchase17/langchain
Author: 
Author-email: 
License: MIT
Location: /home/.local/lib/python3.10/site-packages
Requires: aiohttp, async-timeout, dataclasses-json, langsmith, numexpr, numpy, openapi-schema-pydantic, pydantic, PyYAML, requests, SQLAlchemy, tenacity
Required-by: 

Now new Location is referring to Python3.10 directory

Denver

Answer 2

you probably didn't put your python file location into the enviroment variables.

copy your python file location go to search>edit enviroment enviroment variables>user variables>path>new put the copied python location in the user variables. then try again!

Hufford

if you edit the environment variables, remember to restart the computer – Gadget

Ah sorry forgot to mention - I did also check this! But I found my solution, which I've also posted here. – Ambulatory

Answer 3

when installing in your environment try using: python -m pip install langchain

Idun

Answer 4

For future reference, I'm fairly sure this error was caused by pip installing files in the incorrect directory. Make sure the target directory is where your sys.path folder is, as sometimes these can vary! Thanks to everyone who provided advice.

Ambulatory

You're on track using a venv. But you have to make sure the venv you created is activated so when you install libraries they are installing into that specific virtual environment. Then, when you go to import in your script, make sure wherever you're running the code (VSCode, terminal, etc.), that you are using the python instance associated with the virtual env as well. – Jew

Answer 5

If you are running the code in VS and you have more than one Python version, please check if the bottom right side of the VS Window the version of Python you are using.

Eskimo

Answer 6

Solved the issue by creating a virtual environment first and then installing langchain.

Open an empty folder in VSCode then in terminal:

1. Create a new virtual environment python -m venv myvirtenv where myvirtenv is the name of your virtual environment.

2. In terminal type myvirtenv/Scripts/activate to activate your virtual environment. (If this does not work then type cd .\myvirtenv\Scripts and hit enter, type ./activate hit enter and then type cd ../.. ) . Now your virtual environment should be activated in VScode.

3. Type pip install langchain and hit enter.

Bluecollar

no, that does not work – Gravestone

Answer 7

!pip install langchain

Install the Langchain libary.

You can install it by using pip and go in your terminal and type in the code

Holcomb

Answer 8

• First, you can run this code in your terminal: pip show langchain. If the langchain is not present on your library, just run pip install langchain. You should also check version python, the requirement python version is ≥ 3.8. 1 and <4.0. Quick installation Installation Langchain

I usually run langchian with python 3.11, my steps are as follows:

1. conda create --name my_env python=3.11
2. conda activate my_env
3. pip install langchain
4. pip show langchain

Ioneionesco