How do I fix "ModuleNotFoundError: No module named 'lib2to3'"?

Replace lib2to3-based fixers with a maintained concrete-syntax-tree library: `LibCST` or `parso`. If a dependency pulled in lib2to3 transitively, upgrade it — most have dropped it. For a one-off Python 2→3 conversion, run 2to3 from an older Python (≤3.12) before upgrading the runtime. Re-test on Python 3.13. Source: https://docs.python.org/3/whatsnew/3.13.html

Python 3.13

ModuleNotFoundError: No module named 'lib2to3'

ModuleNotFoundError: No module named 'lib2to3'

What it means

lib2to3 (and the 2to3 tool) were removed in Python 3.13 (PEP 594).

Why it happens

lib2to3 relied on a grammar that couldn't track new syntax; deprecated in 3.11, removed in 3.13. Build tooling or a dependency that imported lib2to3 (often as a code fixer) breaks on a python3.13 runtime.

How to fix it

Replace lib2to3-based fixers with a maintained concrete-syntax-tree library: `LibCST` or `parso`.
If a dependency pulled in lib2to3 transitively, upgrade it — most have dropped it.
For a one-off Python 2→3 conversion, run 2to3 from an older Python (≤3.12) before upgrading the runtime.
Re-test on Python 3.13.

Related deadline: Lambda Python 3.11 EOL — 2027-07-31.

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Primary source: https://docs.python.org/3/whatsnew/3.13.html

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