JSON errors can waste hours of developer time. You're debugging, searching Stack Overflow, trying different fixes - all while your application is broken.
We've analyzed thousands of JSON errors and identified the top 10 JSON errors that waste the most developer time. Learn why each error happens, how to fix it quickly, and how to prevent it. Use our free JSON Fixer to fix these errors in seconds.
The Top 10 Time-Wasting JSON Errors
Unexpected token <
Why It Happens:
HTML error page returned instead of JSON
Quick Fix:
Check API endpoint, verify Content-Type header
Unexpected end of JSON input
Why It Happens:
Missing closing braces or truncated response
Quick Fix:
Add missing closing braces, check network request completion
Expected ',' or {'}'} after property value
Why It Happens:
Missing comma between properties or trailing comma
Quick Fix:
Add missing commas or remove trailing commas
Invalid control character
Why It Happens:
Unescaped newlines, tabs, or control characters
Quick Fix:
Escape special characters or use JSON.stringify()
Unexpected token {'}'} in JSON
Why It Happens:
Trailing comma before closing brace
Quick Fix:
Remove trailing comma
Unexpected token ' in JSON
Why It Happens:
Single quotes instead of double quotes
Quick Fix:
Replace single quotes with double quotes
Unexpected token / in JSON
Why It Happens:
Comments in JSON (not allowed)
Quick Fix:
Remove all // and /* */ comments
Unexpected token u in JSON
Why It Happens:
undefined value (not valid in JSON)
Quick Fix:
Replace undefined with null or omit property
Unexpected number in JSON
Why It Happens:
NaN or Infinity values
Quick Fix:
Replace with null or valid number
Unexpected non-whitespace character
Why It Happens:
Invalid characters or encoding issues
Quick Fix:
Check encoding, remove invalid characters
Prevention Tips
Always Validate JSON
Use our JSON Validator before using JSON in production.
Use JSON.stringify()
Never build JSON manually - use proper serialization.
Handle Errors Gracefully
Wrap JSON.parse() in try-catch blocks.
Use JSON Fixer as Backup
Keep our JSON Fixer bookmarked for quick fixes.
Fix JSON Errors in Seconds
Don't waste time manually fixing JSON errors. Our free JSON Fixer automatically detects and repairs all 10 errors instantly.