unslothai/unsloth

[Bug] import unsloth failed and shows UnicodeDecodeError

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#2,489 opened on May 6, 2025

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help wanted

Description

Hi, I would like to try the latest Mistral finetuning script on my local machine. I am currently using WSL with Ubuntu 24.04.1 LTS and conda virtual environment to run unsloth

I had tried other scripts on unsloth before and they work well. However, this time when I run the command "pip install unsloth vllm==0.8.2", everything messed up and I could not even import unsloth...

When I import unsloth, it shows UnicodeDecodeError: 'utf-8' codec can't decode byte 0xf8 in position 0: invalid start byte

I tried to everything like reinstall unsloth, reinstall virtual env and unsloth, ...etc, but nothing works...

Image

Could you help me out with this issue? Thanks a lot!

Contributor guide

Tech stack
python
Domain
machine learning
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
needs maintainer response
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic Python knowledgeconda environment setup
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the UnicodeDecodeError occurring when importing unsloth after installing with vllm. Check the init .py or any file that loads a non UTF 8 encoded file. The error suggests a byte 0xf8 (invalid start byte) which may come from a corrupted installation or a machine specific encoding issue. Recommend trying a fresh virtual environment without vllm, or checking the installed package files for encoding anomalies. Also, look at the unsloth source code on GitHub for any known encoding fixes.
[Bug] import unsloth failed and shows UnicodeDecodeError · unslothai/unsloth#2489 | Good First Issue