I can't save a list - python-3.x

Question

import tkinter as tk
list = []
def add():
element = entry.get()
entry.delete(0, 1000)
list.append(element)
def save():
with open("save.txt", "w") as f:
for element in list:
f.write(element + ",")
root = tk.Tk()
frameList = tk.Frame(root)
frameList.pack()
entry = tk.Entry(root)
entry.pack()
btnAdd = tk.Button(root, text="add", command=add)
btnAdd.pack(pady=5)
btnSave = tk.Button(root, text="save", command=save)
btnSave.pack()
root.mainloop()
this code give me this error when I save:
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1705, in __call__
return self.func(*args)
File "C:/Users/HP/Desktop/python/github/write.py", line 11, in save
with open("save.txt", "w") as f:
FileNotFoundError: [Errno 2] No such file or directory: 'save.txt'
and if I create the file "save.txt" it says:
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "C:\Users\HP\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1705, in __call__
return self.func(*args)
File "C:/Users/HP/Desktop/python/github/write.py", line 13, in save
f.write(element + ",")
OSError: [Errno 9] Bad file descriptor
please, can you help me to solve this problem?
sorry for this last sentence but I have to add some "not code" to publish the question, so I will say some random stuff from now, sorry