How do I fix 'Object of type datetime is not JSON serializable' in Python?

How it was checked: Reproduced the TypeError; both default=str and isoformat() serialize correctly.

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python
json

Fix

json can't encode datetime objects. Options: 1. Convert explicitly: value.isoformat() gives '2026-01-01T00:00:00' (best for APIs). 2. Quick fix: json.dumps(data, default=str), which uses str() on anything unknown. 3. Custom encoder: subclass json.JSONEncoder and return o.isoformat() for datetime/date in default(). When reading back, parse with datetime.fromisoformat().

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