TypeError: not all arguments converted during string formatting

The error "TypeError: not all arguments converted during string formatting" typically occurs when there's a mismatch between the string formatting placeholders in a string and the values provided to replace those placeholders. This issue often arises with the % operator or .format() method in Python.

Here are some common causes of this error:

1. Mismatch in number of placeholders and values:

For example:

print("My name is %s and my age is %d" % ("John"))

This will raise the error because the format string expects two placeholders (%s for string and %d for integer), but only one argument is provided ("John").

Fix: Make sure the number of arguments matches the number of placeholders.

print("My name is %s and my age is %d" % ("John", 30))

2. Incorrect use of % for non-formatting purposes:

For example:

query = "SELECT * FROM users WHERE name = %s"
cursor.execute(query % ("John"))

This can cause an error if the %s is intended as a SQL placeholder, but the query is formatted like a string.

Fix: Use parameterized queries to avoid issues:

query = "SELECT * FROM users WHERE name = %s"
cursor.execute(query, ("John",))

3. Using % in strings when you don’t intend to format:

If you just want to include a literal % in the string but use it as a formatting symbol, you need to escape it:

print("The discount is 50%")

If the string uses formatting, the % must be escaped like this:

print("The discount is 50%%")

4. Mixing .format() or f-strings with % formatting:

For example:

print("My name is {} and my age is %d".format("John", 30))

This can cause an error since it's mixing the two formatting styles. Stick to one style, such as .format():

print("My name is {} and my age is {}".format("John", 30))

Review your code for these common issues, and the error should be resolved. Let me know if you need help with a specific part of the code!