Hacktoberfest 2026: as issues que os mantenedores marcaram para outubro, abertas e boas para iniciantes. Ver issues do Hacktoberfest

Windows: python.exe fails to start from a long path because of DLL manifests

Aberta
  • Algo errado?
#160,624 0 comentários 0 reações 0 responsáveis Ver no GitHub

Mantenedores costumam responder em até 1 dia

Ninguém assumiu esta issue ainda.

Avaliação

Dificuldade
2/5
Tempo estimado
1-3 horas
Facilidade para iniciantes
28/100
Tipo de issue
Bug
Clareza
Claramente especificada
Status de atividade
Ativa
Stack de tecnologia
python
Domínio
build-system

Direção de pesquisa

Read PC/python_nt.rc and PC/sqlite3.rc, then inspect the executable resource scripts to compare how manifests are embedded. The proposed change removes the ID 2 manifest resource and its fallback define from the two DLL resource scripts; keep the executable manifests at ID 1. Done means DLLs no longer embed that manifest while the executables retain theirs, and long-path startup and extension imports work on Windows.

Escrita pelo modelo de indexação a partir do texto da issue.

Descrição

build OS-windows type-bug
Bug report
Problem

python.exe fails to start with STATUS_NAME_TOO_LONG once its path is 247 characters or longer, even with LongPathsEnabled=1. It turns out this is actually from loading the DLL, not from python.exe itself.

Extension modules like _ctypes and _ssl also fail to import when the install is at a long path.

Cause

The build is creating DLLs with a manifest, and as noted in #126929, Windows can't load a DLL with an embedded manifest from a path near MAX_PATH.

Since about 2010, the manifest doesn't do anything in a DLL. Windows takes the supported OS versions and the Common Controls dependency from the EXE's manifest, not a DLL's.

History

DLLs used to need a manifest. With Visual C++ 2008, which Python 2.6 through 3.2 were built with, a DLL had to declare its dependency on the C runtime in an embedded manifest to find it. However, Visual C++ 2010 stopped using manifests to find the C runtime, so DLLs haven't needed one since.

#67207 (bpo-23018) added the manifest to python_nt.rc in 2015, at the same time as the one for python[w].exe, to declare supportedOS so that GetVersion would stop reporting Windows 8 on newer versions.

In 2016, #71496 (bpo-27309) added the Common Controls dependency so that tkinter's native dialogs would get the right styles. From that change: "Windows needs to load a different version of a particular DLL for the entire process." However, that's only information that the process needs, not the DLLs.

#71918 (bpo-27731) added longPathAware later that year.

Where the manifest comes from now

PC/python_nt.rc embeds PC/python.manifest as resource ID 2, and pythoncore, python3dll, and every extension module project in PCbuild use that resource script. PC/sqlite3.rc does the same for sqlite3.dll.

Possible Solution

Remove the 2 RT_MANIFEST "python.manifest" line, and the RT_MANIFEST fallback define above it, from PC/python_nt.rc and PC/sqlite3.rc. python_exe.rc and pythonw_exe.rc keep embedding the manifest as ID 1.

Note: #156759 doesn't help here, because Windows loads python3XY.dll as a static import of python.exe, before any Python code runs.

CPython versions tested on:

3.14

Operating systems tested on:

Windows

Linked PRs
  • gh-160626
Linguagem predominante
Python
Estrelas
77.7k
Forks
38.3k
Merge médio
13h 43min
PRs com merge (30d)
704

Preparar o ambiente

Abrir no Codespaces

Inicia o contêiner de desenvolvimento do projeto no navegador, com a sua própria conta do GitHub.

Primeiros passos

  1. Leia a issue inteira e depois o guia de contribuição do projeto.
  2. Comente na issue dizendo que vai assumir — evita que duas pessoas façam o mesmo trabalho.
  3. Faça um fork do repositório e trabalhe em uma branch.
  4. Abra um pull request que referencie o número da issue.

Mais de python/cpython

Todas as issues de python/cpython

Issues semelhantes

Mais issues de Python

Receba novas issues na sua caixa de entrada

Um resumo curto de issues do GitHub para quem está começando.