Tkinter error: image "pyimage2" doesn't exist working with classes and frames

Question

i'm working with classes on tkinter and i have this problem:

Traceback (most recent call last):
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.10_3.10.2544.0_x64__qbz5n2kfra8p0\lib\tkinter\__init__.py", line 1921, in __call__
    return self.func(*args)
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\venv\lib\site-packages\customtkinter\windows\widgets\ctk_button.py", line 549, in _clicked
    self._command()
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\input_frame.py", line 88, in go_back
    from main import SerialFrame
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\main.py", line 126, in <module>
    SerialFrame(root).place(x=25, y=50)
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\main.py", line 20, in __init__
    self.createWidgetsMain()
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\main.py", line 101, in createWidgetsMain
    refresh_serials = customtkinter.CTkButton(master=self, command=refresh_menu, image=my_image, width=20,
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\venv\lib\site-packages\customtkinter\windows\widgets\ctk_button.py", line 106, in __init__
    self._draw()
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\venv\lib\site-packages\customtkinter\windows\widgets\ctk_button.py", line 261, in _draw
    self._update_image()  # set image
  File "D:\PYCHARM\pycharmprojects\lumacol_frontend\venv\lib\site-packages\customtkinter\windows\widgets\ctk_button.py", line 172, in _update_image
    self._image_label.configure(image=self._image.create_scaled_photo_image(self._get_widget_scaling(),
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.10_3.10.2544.0_x64__qbz5n2kfra8p0\lib\tkinter\__init__.py", line 1675, in configure
    return self._configure('configure', cnf, kw)
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.10_3.10.2544.0_x64__qbz5n2kfra8p0\lib\tkinter\__init__.py", line 1665, in _configure
    self.tk.call(_flatten((self._w, cmd)) + self._options(cnf))
_tkinter.TclError: image "pyimage2" doesn't exist

This is the code on my application and explanation about how it should work:

First of all, i have a file with the class SerialFrame, and the creation of the window and the frame:

class SerialFrame(customtkinter.CTkFrame):

# CONSTRUCTOR FOR THE FRAME
def __init__(self, master, *args, **kwargs):
    super(SerialFrame, self).__init__(master)
    self.master = master
    self.serial_port = ""
    self.configure(width=400, height=400)
    self.createWidgetsMain()

# METHOD TO CREATE ALL WIDGETS
def createWidgetsMain(self):
    ...

# CREATING THE APP
root = customtkinter.CTk()
root.geometry("700x500")
root.title("Lumalcol Conf")
back = backend.MyAppBackend()
# CREATING THE FIRST FRAME CALLING THE CLASS MY APP
SerialFrame(root).place(x=25, y=50)
root.mainloop()

And i have another 2 files with other diferent classes for other frames in similar way.

The problem is when i press a button to go back to the first frame, here is the code in the other classes:

    def go_back():
        self.destroy()
        btn_back.destroy()
        from main import SerialFrame
        SerialFrame(self.master).place(x=25, y=50)

    btn_back = customtkinter.CTkButton(self.master, text="Go Back",
                                       command=go_back, cursor="hand2")
    btn_back.place(x=465, y=400)

Obviously, while coding the app i had many different problems and if you see something that shouldn't be work well, you can tell me.

I think that probably the error would come here. This code is on def createWidgetsMain, on the main file, and the SerialFrame class.

 my_image = customtkinter.CTkImage(light_image=Image.open("images/refresh.png"),
                                          dark_image=Image.open("images/refresh.png"),
                                          size=(20, 20))

        # CREATE REFRESH BUTTON
        refresh_serials = customtkinter.CTkButton(master=self, command=refresh_menu, image=my_image, width=20,
                                                  text="")

I think that when i press the go_back button, on the other classes, it should create a new object of SerialFrame class and place in the root. Obviously, when i create the other frames, i always send the root, the Tk().

Here is the code of the button to go create the other classes (it's inside the createWidgedsMain method):

    def segmented_button_callback(value):

        if value == "Inputs":
            self.destroy()
            input_frame.InputFrame(self.master, back).place(x=75, y=75)

        if value == "Menu":
            try:
                connection = back.get_connection()
                self.destroy()
                menu_frame.MenuFrame(self.master, back).place(x=25, y=75)
            except:
                self.destroy()
                SerialFrame(self.master).place(x=25, y=50)

    segemented_button = customtkinter.CTkSegmentedButton(master=self,
                                                         values=["Menu", "Inputs"],
                                                         command=segmented_button_callback)

All application works well, my only problem is that, thank you. Here are some pics of the app

Answer 1

Since you have the following code inside main.py:

...

# CREATING THE APP
root = customtkinter.CTk()
root.geometry("700x500")
root.title("Lumalcol Conf")
back = backend.MyAppBackend()
# CREATING THE FIRST FRAME CALLING THE CLASS MY APP
SerialFrame(root).place(x=25, y=50)
root.mainloop()

So when the line from main import SerialFrame inside go_back() is executed, another instance of customtkinter.CTk() will be created which causes the exception.

You need to put the code block inside a if __name__ == "__main__" block as below:

...
if __name__ == "__main__":
    # CREATING THE APP
    root = customtkinter.CTk()
    root.geometry("700x500")
    root.title("Lumalcol Conf")
    # CREATING THE FIRST FRAME CALLING THE CLASS MY APP
    SerialFrame(root).place(x=25, y=50)
    root.mainloop()

Then the code block will not be executed when main is imported.