KeyError in Python

The dictionary has no such key. Python names the key it looked for after KeyError.

KeyError: 'name'

Your error

The exact key. Keys have to match exactly: "Ada" and "ada" are different, and so are 1 and "1".
Print the keys. print(data.keys()) shows what the dictionary really holds.
Use get(). data.get(key) gives None, or a default you choose, instead of an error when the key might be missing.

A key has to be written exactly as it was stored, capital letters included.

Broken

ages = {"ada": 36, "alan": 41}
print(ages["Ada"])

KeyError: 'Ada'

Fixed

ages = {"ada": 36, "alan": 41}
print(ages["ada"])

The number 1 and the text "1" are different keys. input() gives text, so convert with int() or str() to match how the keys were stored.

Broken

names = {"1": "one", "2": "two"}
print(names[1])

KeyError: 1

Fixed

names = {"1": "one", "2": "two"}
print(names["1"])

one

counts[word] += 1 reads the old count first, and the first time there isn't one. Start it at 0 with get().

Broken

counts = {}
for word in ["a", "b", "a"]:
    counts[word] += 1
print(counts)

KeyError: 'a'

Fixed

counts = {}
for word in ["a", "b", "a"]:
    counts[word] = counts.get(word, 0) + 1
print(counts)

{'a': 2, 'b': 1}

In the traceback, File "main.py", line 3 says where the error happened. In the editor, click that line to go to it.
Go over the basics: Dictionaries
Other errors: AttributeError, FileNotFoundError, IndentationError, IndexError, ModuleNotFoundError, NameError, RecursionError, SyntaxError, TypeError, UnboundLocalError, ValueError, ZeroDivisionError