python collections ai_generated true

KeyError: 'missing_key'

ID: python/keyerror-dict

Also available as: JSON · Markdown
98%Fix Rate
99%Confidence
50Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
311 active — — —

Root Cause

Dictionary key doesn't exist.

generic

Workarounds

  1. 97% success Use dict.get(key, default) for optional keys 
    data.get('key', 'fallback') returns fallback if key is missing

    Sources: https://docs.python.org/3/library/stdtypes.html#dict.get

  2. 93% success Use 'key in dict' check for required keys 
    if 'key' in data: value = data['key'] else: raise ValueError('missing key')

Dead Ends

Common approaches that don't work:

  1. Using defaultdict everywhere 50% fail

    Changes the dict behavior globally; may mask missing data issues

  2. Adding all possible keys with None defaults upfront 55% fail

    Hides missing data; downstream code gets None instead of useful errors

Error Chain

Frequently confused with: