Can't start new Python release 3.13.0 b1

[bobjalex]

Bug report

Bug description:

py
Fatal Python error: Failed to import encodings module
Python runtime state: core initialized
ModuleNotFoundError: No module named 'encodings'

Current thread 0x00034e24 (most recent call first):

CPython versions tested on:

3.12

Operating systems tested on:

Windows

Linked PRs

• gh-118860: docs: clarify custom build output directory in PCbuild/readme.txt #153382

[bobjalex]

Oops The CPython version was Python 3.13.0 beta 1, of course.

[YTKme]

Description

I've encountered the same error, not sure if this is also the same case. I got this from a fresh compile of Python 3.13.0 on Windows. I wanted to compile to a different directory, so I can test different versions.

Interesting note, the default compiled version works fine under the cpython\PCbuild\<platform> folder, so cpython\PCbuild\amd64 in my case.

Error

C:\Users\Aries\Desktop\Project\Workspace\Python> C:\Tool\Python\3.13.0\python.exe --version
Python 3.13.0+
C:\Users\Aries\Desktop\Project\Workspace\Python> C:\Tool\Python\3.13.0\python.exe
Fatal Python error: Failed to import encodings module
Python runtime state: core initialized
ModuleNotFoundError: No module named 'encodings'

Current thread 0x00005d7c (most recent call first):
  <no Python frame>
C:\Users\Aries\Desktop\Project\Workspace\Python>

Information

• Windows 11 23H2 22631.4169
• Visual Studio 2022 17.11.4
  • MSVC 143 - VS 2022 C++ x64/x86 build tools (latest)
  • Windows 11 SDK (10.0.22621.0)
  • C++ ATL for latest v143 build tools (x86 & x64)
  • C++ Clang Compiler for Windows (17.0.3)
  • MSBuild support for LLVM (clang-cl) toolset (17.11.9.46202)

Workaround

After some searching and research, I found the below workaround seem to fix it, but I have not tested everything. I guess the developers can update the script to enable building to different directory?

• Update the cpython\PCbuild\build.bat script to include property for /p:OutDir=<path> (be mindful how the <path> is formatted with this article, also more note on why cpython\PCbuild\build.bat below)
• Build with .\PCbuild\build.bat using default parameter (or update build.bat with parameter needed?), I had issue with try using the --pgo flag.
• After building, copy the content of cpython\Lib folder to the OutDir path. This should solve the encodings error, but...
• Additionally copy the binary for venvlauncher.exe and venvwlauncher.exe to the venv\scripts\nt folder in the OutDir path. (The venv directory comes from the cpython\Lib) Otherwise you will get the below error when creating virtual environment.

Unable to copy 'C:\\Tool\\Python\\3.13.0\\venv\\scripts\\nt\\venvlauncher.exe' to 'C:\\Users\\Aries\\Desktop\\Project\\Workspace\\Python\\pv\\Scripts\\python.exe'
Unable to copy 'C:\\Tool\\Python\\3.13.0\\venv\\scripts\\nt\\venvwlauncher.exe' to 'C:\\Users\\Aries\\Desktop\\Project\\Workspace\\Python\\pv\\Scripts\\pythonw.exe'
Error: [WinError 2] The system cannot find the file specified

Additional Note

When compiling with --pgo flag using a different OutDir, I got the below error

  _freeze_module.vcxproj -> C:\Tool\Python\3.13.0\_freeze_module.exe
  Killing any running python.exe instances...
C:\Users\Aries\Desktop\Project\Repository\P\cpython\PCbuild\pyproject.props(194,5): error : PGO run did not succeed (no python313!*.pgc files) and there is no data to merge [C:\Users\Aries\Desktop\Project\Rep
ository\P\cpython\PCbuild\pythoncore.vcxproj]

Build FAILED.

C:\Users\Aries\Desktop\Project\Repository\P\cpython\PCbuild\pyproject.props(194,5): error : PGO run did not succeed (no python313!*.pgc files) and there is no data to merge [C:\Users\Aries\Desktop\Project\Rep
ository\P\cpython\PCbuild\pythoncore.vcxproj]
    0 Warning(s)
    1 Error(s)

When compiling with --pgo flag using default OutDir, getting error for test_embed

Running PGInstrument|x64 interpreter...
Using random seed: 283585144
0:00:00 Run 44 tests sequentially in a single process
0:00:00 [ 1/44] test_array
0:00:05 [ 2/44] test_base64
0:00:08 load avg: 3.10 [ 3/44] test_binascii
0:00:08 load avg: 3.10 [ 4/44] test_binop
0:00:08 load avg: 3.10 [ 5/44] test_bisect
0:00:09 load avg: 3.06 [ 6/44] test_bytes
0:00:28 load avg: 2.62 [ 7/44] test_bz2
0:00:31 load avg: 2.80 [ 8/44] test_cmath
0:00:33 load avg: 2.75 [ 9/44] test_codecs
0:00:42 load avg: 2.51 [10/44] test_collections
0:00:49 load avg: 2.38 [11/44] test_complex
0:00:51 load avg: 2.30 [12/44] test_dataclasses
0:00:54 load avg: 2.25 [13/44] test_datetime
0:01:08 load avg: 2.05 [14/44] test_decimal
0:01:37 load avg: 2.03 [15/44] test_difflib
0:01:44 load avg: 2.05 [16/44] test_embed
test test_embed failed
0:02:24 load avg: 2.09 [17/44] test_float -- test_embed failed (37 errors, 5 failures) in 40.3 sec
0:02:25 load avg: 2.06 [18/44] test_fstring

[vstinner]

Can't start new Python release 3.13.0 b1

You should provide more information about your issue:

• Your Windows version
• How did you install Python?
• How did you start Python?

---

@YTKme:

I wanted to compile to a different directory

It seems like /p:OutDir= option is not supported by Python. Why not installing Python using the Windows installer from python.org?

0:01:44 load avg: 2.05 [16/44] test_embed
test test_embed failed

Please re-run test_embed in verbose mode. Something like:

python -m test test_embed -v

[zooba]

Py_OutDir is the property to override if you want to move the outputs, but be aware that they probably won't run from that location (there's a ton of assumptions in the sources about where the source repo is relative to the built files).

If you want to make an install-shaped layout without creating the installer, use the PC/layout script (e.g. python.bat PC/layout --<options>) with the runtime you just built. -h should show you all the options you get, but as it's an internal script, you'll have to experiment/read the sources to fully understand it.

[YTKme]

@YTKme:

I wanted to compile to a different directory

It seems like /p:OutDir= option is not supported by Python. Why not installing Python using the Windows installer from python.org?

I do have instances using Windows installer. I wanted to compile it from scratch to get an understanding of it.

[pranavchoudhary-tech]

I'd like to help document the use of Py_OutDir and PC/layout for customizing the build output directory in PCbuild/readme.txt. I'll open a PR shortly.