AttributeError: 'NoneType' object has no attribute 'get'

[NArshad]

How to correct what is written below:

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\Dani Brothers\Anaconda3\lib\tkinter\__init__.py", line 1705, in __call__
    return self.func(*args)
  File "D:/Python/Book Bank/New folder/PyCharm/Final/Excel.py", line 57, in SaveBook
    e_pissue.get(),
AttributeError: 'NoneType' object has no attribute 'get'

Process finished with exit code 0