Errors/Python

JSONDecodeError: Invalid JSON

json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

Quick Answer

The string is not valid JSON. Common causes include empty strings, HTML error pages, single quotes, and trailing commas. Validate the string before parsing.

Why This Happens

json.loads() strictly follows the JSON specification. Python uses True/False but JSON uses true/false. Python allows single quotes but JSON requires double quotes.

The Problem

import json
data = json.loads('')
data = json.loads("{'name': 'Alice'}")

The Fix

import json
raw = get_response()
if raw:
    data = json.loads(raw)

# Use double quotes:
data = json.loads('{"name": "Alice"}')

Step-by-Step Fix

  1. 1

    Inspect the raw string

    Print the string before parsing to see its actual content.

  2. 2

    Check for empty responses

    Add 'if response.text:' before parsing.

  3. 3

    Use json.dumps() for Python objects

    Convert Python dicts to JSON with json.dumps().

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