can only concatenate str (not "list") to str

This error occurs when you try to concatenate a string and a list using the + operator. Python does not allow this operation because it cannot concatenate two different data types.

To resolve this error, you need to convert the list to a string before concatenating it with the other string. You can use the join() method to convert the list to a string and then concatenate it with the other string.

Here's an example:

my_list = ['hello', 'world']
my_string = ' '.join(my_list)  # converts list to string with a space separator
print(my_string + '!')

Output:

hello world!

In this example, we first convert the list `my_list` to a string using the join() method, which adds a space separator between the two words. Then we concatenate the resulting string with the exclamation mark using the + operator.