win 10 Python-3.13.0 tkinter fails in venv

[replabrobin]

Bug report

Bug description:

Installed python 3.13.0 in windows 10 at c:\python313

created venv at c:\users\rptla\tmp\py313

Tkinter based app failed to start in the venv. After testing tkinter I see these results ie error in venv starting Tk() wotks in installed.

In the venv

(py313) C:\Users\rptla\tmp\py313>python
Python 3.13.0 (tags/v3.13.0:60403a5, Oct  7 2024, 09:38:07) [MSC v.1941 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import tkinter
>>> root = tkinter.Tk()
Traceback (most recent call last):
  File "<python-input-1>", line 1, in <module>
    root = tkinter.Tk()
  File "C:\python313\Lib\tkinter\__init__.py", line 2459, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
              ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_tkinter.TclError: Can't find a usable init.tcl in the following directories:
    C:/python313/lib/tcl8.6 C:/lib/tcl8.6 C:/lib/tcl8.6 C:/library C:/library C:/tcl8.6.14/library C:/tcl8.6.14/library



This probably means that Tcl wasn't installed properly.

>>>

in installed python

C:\Python313\Lib\tkinter>\python313\python
Python 3.13.0 (tags/v3.13.0:60403a5, Oct  7 2024, 09:38:07) [MSC v.1941 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import tkinter
>>> root=tkinter.Tk()
>>>

CPython versions tested on:

3.13

Operating systems tested on:

Windows

Linked PRs

• gh-125235: Keep _tkinter TCL paths pointing to base installation on Windows #125250
• [3.13] gh-125235: Keep _tkinter TCL paths pointing to base installation on Windows (GH-125250) #125312

[replabrobin]

FWIW i found that setting TCL_LIBRARY to point at the installation\tcl\tcl8.6 prevents Tk() from raising an exception.

However, running my app leaves a command window visible which it should not. I tried running the app directly with python w ie

pythonw -mmodule.module.app

that still leaves the command window visible.

I tried various settings for TK_LIBRARY, but that dis not help.

[y5c4l3]

Behaviors of TCL paths on Windows are sort of different, they look it up at sys.prefix which could be a venv root. PR changes it to sys.base_prefix.

cpython/Modules/_tkinter.c

Line 146 in f9ae5d1

PyObject *prefix = PySys_GetObject("prefix"); // borrowed reference

[RicardoEscobar]

My guess is that this requieres a 3.13.1 patch to fix it.

[joshburnett]

I see the same failure in Windows 11 as well, running in a venv:

Python 3.13.0 (tags/v3.13.0:60403a5, Oct  7 2024, 09:38:07) [MSC v.1941 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import tkinter
>>> root = tkinter.Tk()
Traceback (most recent call last):
  File "<python-input-2>", line 1, in <module>
    root = tkinter.Tk()
  File "C:\Users\jburnett1\AppData\Local\Programs\Python\Python313\Lib\tkinter\__init__.py", line 2459, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
              ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_tkinter.TclError: Can't find a usable init.tcl in the following directories:
    C:/Users/MY_USER_NAME/AppData/Local/Programs/Python/Python313/lib/tcl8.6 C:/Users/jburnett1/AppData/Local/Programs/Python/lib/tcl8.6 C:/Users/MY_USER_NAMEAppData/Local/Programs/lib/tcl8.6 C:/Users/MY_USER_NAME/AppData/Local/Programs/Python/library C:/Users/MY_USER_NAME/AppData/Local/Programs/library C:/Users/MY_USER_NAME/AppData/Local/Programs/tcl8.6.14/library C:/Users/MY_USER_NAME/AppData/Local/tcl8.6.14/library

Running in the base Python install works OK.

My python.org-installed version is installed for just my user, and I do see the above-mentioned init.tcl file in C:\Users\MY_USER_NAME\AppData\Local\Programs\Python\Python313\tcl\tcl8.6 but this directory is not listed in the traceback as one of the ones being searched.

[y5c4l3]

Bisects to c67121a, cc @vstinner would you mind having a look at my PR? :-)

[vstinner]

On Windows, when I build Python from source, TCL is loaded from externals\tcltk-8.6.15.0 directory using an absolute path, so the bug was not spotted before. Even with a venv, externals\tcltk-8.6.15.0 is found and used.

Thank you for the bug report and the fix.