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[Docs] Fix python specifiers in tutorials#19280

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vacu9708 wants to merge 1 commit intopytorch:mainfrom
vacu9708:fix-conda-python-version
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[Docs] Fix python specifiers in tutorials#19280
vacu9708 wants to merge 1 commit intopytorch:mainfrom
vacu9708:fix-conda-python-version

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@vacu9708 vacu9708 commented May 4, 2026 •
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Fixes #18073 (This issue was already fixed before this PR)

Problem

The setup tutorial prescribes:

conda create -yn executorch python=3.10.0

This version has a CPython bug that leaves PyTorch's LeafSpec's init=False
fields uninitialized. run_decompositions() in ExecuTorch deepcopies the
LeafSpec nodes and crashes.
This breaks the export pipeline (to_edge_transform_and_lower, to_edge, run_decompositions),
which leads to any model export attempt failing unconditionally on Python 3.10.0.

The error message (AttributeError: 'LeafSpec' object has no attribute 'type')
gives no indication that Python version is the cause, making it hard for tutorial followers to diagnose.

Upstream Fix Status

The fix has already landed in PyTorch main via pytorch/pytorch#177154 and is available in recent nightly builds.
However, ExecuTorch currently pins to torch==2.11.
The 2.11 branch was cut before the fix was merged, which means
the upstream fix does not apply until the ExecutTorch's torch pin is bumped to 2.12.
Until then, this PR is necessary to prevent tutorial followers from hitting the bug and getting lost.

Resolution

The CI build script (.ci/docker/build.sh) uses:

PYTHON_VERSION=3.10

conda interprets python=3.10 as a prefix, installing the latest available
3.10.x — currently 3.10.16 — which does not have this bug.
The CPython fix landed in 3.10.1.
This discrepancy (3.10 vs 3.10.0) makes the bug invisible to CI while affecting any user who follows the setup tutorial.

Fix python=3.10.0 -> python=3.10 to align the docs with CI.

Test plan

Not working

conda create -yn executorch3100 python=3.10.0
conda activate executorch3100

Working

conda create -yn executorch310 python=3.10
conda activate executorch310

import torch
from executorch.exir import to_edge_transform_and_lower
from executorch.backends.xnnpack.partition.xnnpack_partitioner import XnnpackPartitioner

class MyModel(torch.nn.Module):
    def forward(self, x):
        return x + 1

# 1. Export your PyTorch model
model = MyModel().eval()
example_inputs = (torch.randn(1, 3, 224, 224),)
exported_program = torch.export.export(model, example_inputs)

# 2. Optimize for target hardware (switch backends with one line)
program = to_edge_transform_and_lower(
    exported_program,
    partitioner=[XnnpackPartitioner()]  # CPU | CoreMLPartitioner() for iOS | QnnPartitioner() for Qualcomm
).to_executorch()

@vacu9708 vacu9708 requested a review from mergennachin as a code owner May 4, 2026 14:02
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pytorch-bot Bot commented May 4, 2026 •
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🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/19280

Note: Links to docs will display an error until the docs builds have been completed.

❗ 1 Active SEVs

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@vacu9708
[Docs] Fix python specifiers in tutorials
cdf8891 
The tutorial pages prescribe 'python=3.10.0', which has a CPython
bug (python/cpython#89683) that leaves PyTorch's LeafSpec's init=False
fields uninitialized. run_decompositions() in ExecuTorch deepcopies the
LeafSpec nodes and crashes, so any model export attempt fails
unconditionally on Python 3.10.0.

The CI pipeline uses PYTHON_VERSION=3.10 in .ci/docker/build.sh, which
conda resolves to the latest 3.10.x (currently 3.10.16) — unaffected by
the bug. This fix aligns the docs with CI.
@vacu9708 vacu9708 force-pushed the fix-conda-python-version branch from a645615 to cdf8891 Compare May 5, 2026 11:01
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vacu9708 commented May 5, 2026

Sorry I included a wrong additional commit by mistake and the CI failed. I'd like to request the approval again.

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@Gasoonjia Gasoonjia Gasoonjia approved these changes

@mergennachin mergennachin Awaiting requested review from mergennachin mergennachin is a code owner

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AttributeError: 'LeafSpec' object has no attribute 'type' when using nightly pytorch

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