PermissionError: [Errno 13] Permission denied: 'file.mp3'

The program runs only twice. Later, the error occurs. I don't know why it works twice and then stops.

import tkinter, sys, pygame
from tkinter import messagebox
from gtts import gTTS

soundfile="file.mp3"

def ex():
    sys.exit()

The main problem is there:

def read():
    t = e.get()
    tts = gTTS(text=t, lang="en")
    tts.save(soundfile)
    pygame.mixer.init(frequency=16000, size=-16, channels=2, buffer=4096)
    pygame.mixer.music.load(soundfile)
    pygame.mixer.music.set_volume(1.0)
    pygame.mixer.music.play(0,0.0)
    while pygame.mixer.music.get_busy()==True:
        continue
    pygame.quit()

Next is the code for the buttons.

def clear():
    e.delete(0, 'end')

main = tkinter.Tk()

e = tkinter.Entry(main, justify = "center")
l = tkinter.Label(main, text = "Write text")
b1 = tkinter.Button(main, text = "Read", command = read)
b2 = tkinter.Button(main, text = "Clear", command = clear)
b3 = tkinter.Button(main, text = "Exit", command = ex)

So, I don't have any idea to fix it.