KeyError: key not found in a dictionary

A KeyError means you asked a dictionary for a key it does not contain. The message shows the missing key.

prices = {"tea": 12, "samosa": 15}
print(prices["coffee"])

Traceback (most recent call last):
  File "example.py", line 2, in <module>
    print(prices["coffee"])
          ~~~~~~^^^^^^^^^^
KeyError: 'coffee'

Cause 1: the key really is not there

The simplest case. The data does not contain what you expected. Print the keys to see what the dictionary holds.

prices = {"tea": 12, "samosa": 15}
print(list(prices))

['tea', 'samosa']

Cause 2: spelling, capitals or spaces

Keys must match exactly. "Tea", "tea" and "tea " with a space at the end are three different keys.

prices = {"tea": 12}
print(prices["Tea"])

Traceback (most recent call last):
  File "example.py", line 2, in <module>
    print(prices["Tea"])
          ~~~~~~^^^^^^^
KeyError: 'Tea'

When keys come from what users type, clean both sides the same way before storing and before looking up: key.strip().lower().

Cause 3: the wrong type of key

roll = {1: "Asha", 2: "Ravi"}
print(roll["1"])

Traceback (most recent call last):
  File "example.py", line 2, in <module>
    print(roll["1"])
          ~~~~^^^^^
KeyError: '1'

The key is the number 1. The lookup used the text "1", which is what input gives. Convert with int before looking up. In the error message, quotation marks around the key tell you it is a string.

Cause 4: forgetting quotation marks is a different error

If you write prices[tea] without quotation marks, Python looks for a variable called tea. That gives a NameError, not a KeyError, unless such a variable happens to exist.

Safe way 1: get

The get method returns None when the key is missing, or a default value that you choose.

prices = {"tea": 12, "samosa": 15}
print(prices.get("coffee"))
print(prices.get("coffee", 0))
print(prices.get("tea", 0))

None
0
12

Use get whenever a missing key is normal and you have a sensible fallback.

Safe way 2: check with in

prices = {"tea": 12, "samosa": 15}
item = "coffee"
if item in prices:
    print(prices[item])
else:
    print(item, "is not on the menu")

coffee is not on the menu

Safe way 3: try and except

prices = {"tea": 12, "samosa": 15}
try:
    print(prices["coffee"])
except KeyError as e:
    print("No such item:", e)

No such item: 'coffee'

The counting pattern

This error is very common in code that counts things, because the first time a word is seen, it has no entry yet.

count = {}
for word in ["tea", "tea"]:
    count[word] = count[word] + 1

Traceback (most recent call last):
  File "example.py", line 3, in <module>
    count[word] = count[word] + 1
                  ~~~~~^^^^^^
KeyError: 'tea'

Use get with a default of 0.

count = {}
for word in ["tea", "coffee", "tea"]:
    count[word] = count.get(word, 0) + 1
print(count)

{'tea': 2, 'coffee': 1}

Deleting a key that is not there

del prices["coffee"] and prices.pop("coffee") both raise a KeyError when the key is missing. Give pop a second argument to make it safe: prices.pop("coffee", None).

Which approach when?

• A missing key means a bug in your program: use square brackets and let the error show you the bug.
• A missing key is expected: use get with a default.
• You need to do something quite different when the key is missing: use in or try.

More about dictionaries is in lesson 14.

Other error messages

Examples on this page were run with Python 3.14 on 12 November 2026. The output shown is the real output.

This is an independent learning site. It is not connected with or approved by the Python Software Foundation. "Python" is a trademark of the Python Software Foundation and is used here only to name the language.