_tkinter.TclError: couldn't recognize image data

[Xenoman81]

Trying to open any NetCDF file, I get this tkinter error:

Traceback (most recent call last):
  File "/gpfs/work/-/temp/nc2/venv/bin/nc2", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/gpfs/work/-/temp/nc2/venv/lib/python3.12/site-packages/nc2/nc2.py", line 1367, in main
    root = tb.Window(themename='darkly')
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/gpfs/work/-/temp/nc2/venv/lib/python3.12/site-packages/ttkbootstrap/window.py", line 231, in __init__
    self._icon = tkinter.PhotoImage(master=self, data=Icon.icon)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/apps/shared/taifun/x86_64/apps/DATAPROCESSING/python/3.12.7/system/lib/python3.12/tkinter/__init__.py", line 4162, in __init__
    Image.__init__(self, 'photo', name, cnf, master, **kw)
  File "/apps/shared/taifun/x86_64/apps/DATAPROCESSING/python/3.12.7/system/lib/python3.12/tkinter/__init__.py", line 4109, in __init__
    self.tk.call(('image', 'create', imgtype, name,) + options)
_tkinter.TclError: couldn't recognize image data

This is clearly not caused by NC2 code, but by tkinter and/or ttkbootstrap. A quick search points to a TCL version issue, apparently requiring at least TCL 8.6:.

The reason for this is the limited image format support of TCL, as discussed here. And although Pillow is a NC2 dependency, it does not resolve this issue. Is seems that only upgrading from my TCL 8.5 to >=8.6 would help, but this requires admin rights.

A way to reproduce this error, or to confirm the correct functioning

from tkinter import *
root = Tk()

canv = Canvas(root, width=80, height=80, bg='white')
canv.grid(row=2, column=3)

img = PhotoImage(data=Icon.warning)  # It fails here already

canv.create_image(20,20, anchor=NW, image=img)

mainloop()