PermissionError: [Errno 13] Permission denied: (After one minute execution, the program halts)

Question

After the execution takes like a minute, I've been getting this error. I think it is not about path line issue because all the pics are in current folder. Since I've been getting this one minute later, I got confused. Can anyone help me out of here?

class PVCScreen (Screen):
def __init__(self, gameDisplay, screenX, screenY):
    self._gameDisplay = gameDisplay
    self._screenX = screenX
    self._screenY = screenY
    self._prompt_level = Button(gameDisplay, (5 * screenX // 24), (screenY // 18), (7 * screenX // 12), (screenY // 4), "prompt_level.jpg", "resized_prompt_level.jpg")
    self._easy_button = Button(gameDisplay, (5 * screenX // 24), (screenY // 2.25), (5 * screenX // 32), (5 * screenY // 36), "easy_button.png", "resized_easy_button.png")
    self._medium_button = Button(gameDisplay, (61 * screenX // 96), (screenY // 2.25), (5 * screenX // 32), (5 * screenY // 36), "medium_button.png", "resized_medium_button.png")
    self._hard_button = Button(gameDisplay, (5 * screenX // 24), (screenY // 1.25), (5 * screenX // 32), (5 * screenY // 36), "hard_button.png", "resized_hard_button.png")
    self._extreme_button = Button(gameDisplay, (61 * screenX // 96), (screenY // 1.25), (5 * screenX // 32), (5 * screenY // 36), "extreme_button.gif", "resized_extreme_button.gif")

I'm getting that error any of the Button that I've made.

Here is the Button class:

class Button:
def __init__(self, display, x, y, width, height, img_name_old, img_name_new):
    self._display = display
    self._x = x
    self._y = y
    self._width = width
    self._height = height
    self.resizeImage(img_name_old, img_name_new, width, height)
    button_image = pygame.image.load(img_name_old)
    display.blit(button_image, [x,y])
    # yukarisina gerek olmayabilir


# new size of the pic is passed as x and y.
def resizeImage(self, img_name_old, img_name_new, width, height):
    img = Image.open(img_name_old)
    img = img.resize((width, height), PIL.Image.ANTIALIAS)
    img.save(img_name_old)
    return img

Thanak you in advance.