ImportError: cannot import name get_column_letter

The function get_column_letter has been relocated in Openpyxl version 2.4 from openpyxl.cell to openpyxl.utils.

The current import is: from openpyxl.utils import get_column_letter

If you do not know which version the end-user has, you can use the following code:

try: 
    from openpyxl.cell import get_column_letter
except ImportError:
    from openpyxl.utils import get_column_letter

from openpyxl.utils import get_column_letter

This is working for Python3 also.