astral-sh/uv

Improve error message on "failed to spawn" where the Python interpreter is missing

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#13992 opened on Jun 12, 2025

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 (4 comments) (0 reactions) (0 assignees)Rust (84,934 stars) (3,111 forks)batch import
enhancementerror messageshelp wanted

Description

Summary

e.g., as reported in https://github.com/astral-sh/uv/issues/13196

The error message when the Python interpreter cannot be found by an entry point is

error: Failed to spawn: `jupyter` Caused by: No such file or directory (os error 2)

We can read the entry point and provide a better error message in this case.

Related #13989

Example

error: Failed to spawn: `jupyter` Caused by: No such file or directory (os error 2)

hint: `jupyter` uses a Python interpreter at `path` which no longer exists

Contributor guide

Tech stack
rustpython
Domain
clideveloper experience
Issue type
feature
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.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic Rust knowledgeUnderstanding of uv error handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Start by examining the error message generation in the entry point spawning logic, likely in the 'uv' crate (e.g., commands or interpreter modules). Look at the related issue #13196 and PR #13989 for context. Identify where the 'Failed to spawn' error is produced and determine how to access the Python interpreter path to include a hint when it is missing.