TypeError: can only concatenate str (not "int") to str

This error occurs when you try to concatenate a string and an integer using the + operator. In Python, you can only concatenate two strings using the + operator, not a string and an integer.

For example, if you have a variable "x" that is an integer and you want to concatenate it with a string "Hello", you will get this error:

x = 5
print("Hello" + x)

To fix this error, you need to convert the integer to a string using the str() function:

x = 5
print("Hello" + str(x))

Output:
Hello5

Now, the integer is converted to a string and can be concatenated with the other string.