Tkinter not installed correctly on Windows 3.15.0b2

[terryjreedy]

Bug report

Bug description:

3.15.0b1 was fine. 3.15.0b2 will not start tk/tcl. Difference must be incomplete upgrade to tk 9.0.

If I run the REPL with either the Start icon or py in a console, import tkinter works but a subsequent t = tkinter.Text() fails with

Traceback (most recent call last):
  File "<python-input-2>", line 1, in <module>
    t = tkinter.Text()
  File "C:\Programs\Python315\Lib\tkinter\__init__.py", line 3857, in __init__
    Widget.__init__(self, master, 'text', cnf, kw)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Programs\Python315\Lib\tkinter\__init__.py", line 2853, in __init__
    self._setup(master, cnf)
    ~~~~~~~~~~~^^^^^^^^^^^^^
  File "C:\Programs\Python315\Lib\tkinter\__init__.py", line 2818, in _setup
    master = _get_default_root()
  File "C:\Programs\Python315\Lib\tkinter\__init__.py", line 330, in _get_default_root
    root = Tk()
  File "C:\Programs\Python315\Lib\tkinter\__init__.py", line 2535, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
              ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_tkinter.TclError: Can't find a usable tk.tcl in the following directories:
    //zipfs:/app/tk_library //zipfs:/lib/tk/tk_library //zipfs:/lib/tk //zipfs:/lib/tcl/tcl_library/tk9.0 //zipfs:/lib/tcl/tk9.0 C:/Programs/lib/tk9.0 C:/Programs/lib/tk9.0 C:/lib/tk9.0 C:/Programs/library

This probably means that tk wasn't installed properly.

The IDLE icon in the start menu does not work. If I pin it to taskbar and click, the blue circle starts and quickly stops. The one for older versions start, quickly stop, and quickly restart until IDLE runs. In a console, py -m idlelib fails at the same _tkinter.create(...) call with the same message.

I have seen a similar message before and I believe the list of directories is obsolete. In a local build, I believe the tcl/tk file needs to be in PCbuild/. My 3.16 build works fine. Installations used to have DLLs/tcl86t.dll and tk86t.dll. 3.15.0b2 has tcl9tk90.dll and tcl90.dll (no t suffix). Is _tkinter.dll looking for those names?

CPython versions tested on:

3.15

Operating systems tested on:

Windows

Linked PRs

• gh-150836: Build Tcl/Tk with noembed on Windows #150888
• gh-150836: Mount embedded Tk ZIP in _tkinter on Windows #151562
• [3.15] gh-150836: Mount embedded Tk ZIP in _tkinter on Windows (GH-151562) #151735

[terryjreedy]

import turtle also works. turtle.Screen() (with the ()s) fails.

[jjhelmus]

I was able to get Tkinter working with an install of 3.15.0b2 on Windows by adjusting the files in the tcl directory.

Specifically in the tcl directory I:

• Extracted the contents of libtcl9.0.3.zip and libtk9.0.3.zip.
• Renamed the tcl_library directory to tcl9.0
• Renamed the existing tk9.0 directory to tk9.0.orig (this could likely be done differently, either deleting or merging)
• Renamed the tk_library to tk9.0

The root issue seems to be that the tcl-tk binary release for 9.0.3.0 uses TclVFS for the tcl and tk libraries which is causing an issue, although the tcl library seems to load fine from the zip file.

[zooba]

@zware FYI (you can have first go at it, but if you haven't got the time then just say and I'm sure someone else will have time)

[zware]

If someone can beat me to it, go for it :)

[jjhelmus]

FWIW I think the Tcl library loads because it is embedded in the DLL:

❯ file tcl90.dll
tcl90.dll: PE32+ executable (DLL) (GUI) x86-64, for MS Windows
❯ unzip -l tcl90.dll | grep init.tcl
warning [tcl90.dll]:  2242048 extra bytes at beginning or within zipfile
  (attempting to process anyway)
    24348  05-12-2026 04:33   tcl_library/init.tcl

[jjhelmus]

A bit more information. The tk_library is embedded in tcl9tk90.dll:

❯ unzip -l tcl9tk90.dll | grep tk.tcl
warning [tcl9tk90.dll]:  1835520 extra bytes at beginning or within zipfile
  (attempting to process anyway)
     7634  05-12-2026 04:33   tk_library/safetk.tcl
    27570  05-12-2026 04:33   tk_library/tk.tcl
     6667  05-12-2026 04:33   tk_library/ttk/ttk.tcl

The DLLs directory does not seem to be searched by Tcl's tcl_findLibrary. Moving tcl9tk90.dll up one directory so it is next to python.exe fixes the issue but is not a solution.

Building tcl/tk with noembed looks promising. I'm trying that out locally.