voxel51/fiftyone

[BUG] Launching the app through pants fails after 1.7.1

Open

#6408 opened on Oct 13, 2025

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buggood first issue

Description

Describe the problem

Launching fiftyone through pants fails starting from version 1.7.1. The app does not find index.html and this is probably due to how pants resolves and packages dependencies. This issue only appears when running through pants. Outside of pants it works perfectly.

Code to reproduce issue

Invoking the following code through pants run script.py

import fiftyone as fo
import fiftyone.zoo as foz

dataset = foz.load_zoo_dataset("quickstart")
session = fo.launch_app(dataset)

session.wait()

Leads to a blank page with "Not found" when opening http://0.0.0.0:5151.

System information

  • Ubuntu 22.04
  • Python version 3.11
  • FiftyOne version >= 1.7.1
  • FiftyOne installed from pip

Other info/logs

The error is the same as in this topic, but it's only when running through pants.

Willingness to contribute

  • Yes. I can contribute a fix for this bug independently
  • [ x ] Yes. I would be willing to contribute a fix for this bug with guidance from the FiftyOne community
  • No. I cannot contribute a bug fix at this time

Contributor guide

Tech stack
python
Domain
full stack
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.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
PythonPants build systemWeb application basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Start by comparing the packaging behavior between FiftyOne versions 1.7.0 and 1.7.1 using pants. Examine how index.html is located and included in the built package. Check the pants BUILD files for any differences that might affect resource inclusion. Also review the linked issue #1633 for similar context.