JSON troubleshooting guide
Most broken JSON fails for a small set of repeat problems. Once you know the patterns, fixing parser errors becomes much faster.
Trailing commas, missing commas, unmatched braces, broken string quotes, and accidental comments account for a large share of invalid JSON in day-to-day work.
Read the first reported line and column, then inspect the surrounding characters. The first error is usually the most useful one; later errors may just be side effects.
Fix syntax first, validate again, then beautify the result so the structure becomes easier to inspect and review.
Trailing commas and quote mistakes are two of the most common issues.
The parser often notices the break later than the original mistake, so inspect the nearby characters too.
Always fix the first reported parser error before looking at later ones.