TypeError: not all arguments converted during string formatting

This error occurs when a string formatting operation has fewer or more placeholders than the number of arguments passed to it. For example:

name = 'John'
age = 25
print('My name is %s and I am %d years old.' % name)

In this code, the `%s` and `%d` are placeholders for a string and an integer, respectively. However, only one argument (`name`) is passed to the string formatting operation, resulting in a `TypeError` since not all arguments are converted.

To fix this error, make sure that the number of placeholders in the string matches the number of arguments passed. For example:

name = 'John'
age = 25
print('My name is %s and I am %d years old.' % (name, age))

In this code, both `name` and `age` are passed as arguments to the string formatting operation, so the error is resolved.