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Different output from importlib.resources.files() in REPL in 3.12 versus 3.13 #121190

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Different output from importlib.resources.files() in REPL in 3.12 versus 3.13#121190
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stdlibStandard Library Python modules in the Lib/ directorytopic-replRelated to the interactive shelltype-bugAn unexpected behavior, bug, or error

Description

@danielhollas
danielhollas
opened on Jun 30, 2024

Bug report

Bug description:

Running importlib.resources.files() without specifying the anchor parameter in interactive REPL in Python 3.12 raises a rather unhelpful error:

>>> import importlib.resources
>>> importlib.resources.files()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.12/importlib/resources/_common.py", line 45, in wrapper
    return func()
           ^^^^^^
  File "/usr/lib64/python3.12/importlib/resources/_common.py", line 56, in files
    return from_package(resolve(anchor))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/importlib/resources/_common.py", line 113, in from_package
    reader = spec.loader.get_resource_reader(spec.name)
                                             ^^^^^^^^^
  File "/usr/lib64/python3.12/importlib/resources/_adapters.py", line 17, in __getattr__
    return getattr(self.spec, name)
           ^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'name'

It would be nice to return something more helpful. The documentation doesn't mention that this function can raise, so I am assuming that raising AttributeError is not part of the public API?

However, on a locally built Python from current main branch, this call returns a path to Lib/_pyrepl. Even more surprising though is that this also happens when running the OLD REPL with TERM=dumb ./python

❯ TERM=dumb ./python 
Python 3.14.0a0 (heads/main:1a84bdc237, Jun 30 2024, 21:44:46) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: terminal doesn't have the required clear capability
>>> import importlib.resources
>>> importlib.resources.files()
PosixPath('/home/hollas/software/cpython/Lib/_pyrepl')

CPython versions tested on:

3.12, CPython main branch

Operating systems tested on:

Linux

Linked PRs

Activity

  1. danielhollas
    added
    type-bugAn unexpected behavior, bug, or error
    on Jun 30, 2024
  2. AlexWaygood
    added
    topic-replRelated to the interactive shell
    on Jun 30, 2024

  3. lysnikolaou commented on Jul 1, 2024

    @lysnikolaou
    lysnikolaou
    on Jul 1, 2024
    Member

    Even more surprising though is that this also happens when running the OLD REPL with TERM=dumb ./python

    TERM=dumb does not enable the old REPL. The env var is called PYTHON_BASIC_REPL.

  4. danielhollas commented on Jul 1, 2024

    @danielhollas
    danielhollas
    on Jul 1, 2024
    ContributorAuthor

    TERM=dumb does not enable the old REPL. The env var is called PYTHON_BASIC_REPL.

    Well, while it may not enable it explicitly, implicitly it does since pyrepl will not start with this type of terminal.

    ❯ TERM=DUMB ./python 
Python 3.14.0a0 (heads/main:1a84bdc237, Jun 30 2024, 21:44:46) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: setupterm: could not find terminal
>>> import importlib.resources
>>> importlib.resources.files()
PosixPath('/home/hollas/software/cpython/Lib/_pyrepl')

    But you are right that actually using PYTHON_BASIC_REPL will actually run the old REPL directly, and will produce the same behaviour as in 3.12

    ❯ PYTHON_BASIC_REPL=1 ./python 
Python 3.14.0a0 (heads/main:1a84bdc237, Jun 30 2024, 21:44:46) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import importlib.resources
>>> importlib.resources.files()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    importlib.resources.files()
    ~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/hollas/software/cpython/Lib/importlib/resources/_common.py", line 45, in wrapper
    return func()
  File "/home/hollas/software/cpython/Lib/importlib/resources/_common.py", line 56, in files
    return from_package(resolve(anchor))
  File "/home/hollas/software/cpython/Lib/importlib/resources/_common.py", line 116, in from_package
    reader = spec.loader.get_resource_reader(spec.name)
                                             ^^^^^^^^^
  File "/home/hollas/software/cpython/Lib/importlib/resources/_adapters.py", line 17, in __getattr__
    return getattr(self.spec, name)
AttributeError: 'NoneType' object has no attribute 'name'
>>>

    Note that I am not saying that the pyrepl behaviour is wrong here, just noting the difference. If anything, I'd change the behaviour in the old REPL so that at least it fails a bit more gracefully (not an obscure AttributeError).

  5. whitphx commented on May 22, 2025

    @whitphx
    whitphx
    on May 22, 2025
    Contributor

    #134275 should fix the new REPL's different behavior than the old one,
    while the issue below still is there

    It would be nice to return something more helpful. The documentation doesn't mention that this function can raise, so I am assuming that raising AttributeError is not part of the public API?

  6. picnixz
    added
    stdlibStandard Library Python modules in the Lib/ directory
    on May 23, 2025

  7. whitphx commented on Sep 5, 2025

    @whitphx
    whitphx
    on Sep 5, 2025
    Contributor

    Hi from PyConTW sprint.

    SpecLoaderAdapter accesses spec's attributes such as spec.name

    cpython/Lib/importlib/resources/_adapters.py

    Line 17 in fc0305a

    return getattr(self.spec, name)

    while spec can be None when the package is __main__ as documented.

    cpython/Lib/importlib/resources/_adapters.py

    Line 168 in fc0305a

    return SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)

    importlib.resources._common.from_package(package) needs to take care of the case where package.__spec__ is None.

    Let me take a closer look...

    >>> import importlib_resources
>>> importlib_resources.files()
Traceback (most recent call last):
  File "<python-input-1>", line 1, in <module>
    importlib_resources.files()
    ~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/workspace/cpython/.venv/lib/python3.15/site-packages/importlib_resources/_common.py", line 45, in wrapper
    return func()
  File "/workspace/cpython/.venv/lib/python3.15/site-packages/importlib_resources/_common.py", line 56, in files
    return from_package(resolve(anchor))
  File "/workspace/cpython/.venv/lib/python3.15/site-packages/importlib_resources/_common.py", line 117, in from_package
    reader = spec.loader.get_resource_reader(spec.name)
                                             ^^^^^^^^^
  File "/workspace/cpython/.venv/lib/python3.15/site-packages/importlib_resources/_adapters.py", line 17, in __getattr__
    return getattr(self.spec, name)
AttributeError: 'NoneType' object has no attribute 'name'
  8. whitphx
    added a commit that references this issue on Sep 10, 2025

    Merge branch 'main' into pythongh-121190

    06b8233
  9. jaraco
    added 2 commits that reference this issue on Apr 12, 2026

    pythongh-121190: Emit a better error message in `importlib.resources.…

    c95fb7d

    gh-121190: Emit a better error message from `importlib.resources.file…

    480edc1

  10. jaraco commented on Apr 12, 2026

    @jaraco
    jaraco
    on Apr 12, 2026
    Member

    This change should be included in Python 3.15. Thanks for the patience awaiting merge.

  11. jaraco
    closed this as completedon Apr 12, 2026
  12. prakashsellathurai
    added a commit that references this issue on Apr 13, 2026

    Revert "pythongh-121190: Emit a better error message from `importlib.…

    c1823d9
  13. ljfp
    added a commit that references this issue on Apr 25, 2026

    pythongh-121190: Emit a better error message from `importlib.resource…

    1e1fb00
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