How to Read a JSON Validation Error and Actually Fix It
A JSON validation error typically reports a specific line and character position where parsing failed — the most common causes are a missing or extra comma, unmatched brackets or braces, or an unquoted key or string value, and checking the exact position reported (and the character just before it) usually reveals the specific issue.
JSON error messages can look cryptic at first, but they're actually quite precise once you know what to look for at the reported position.
The most common error causes
A trailing comma after the last item in an object or array (valid in some languages but not standard JSON), a missing comma between two items, unmatched opening or closing brackets/braces, and an unquoted key or string value (JSON requires double quotes, not single quotes, around strings and keys) account for the large majority of validation errors.
Using the reported position
Most validators report a specific line number and character position for the parse failure — checking that exact location, and often the character immediately before it, usually reveals the issue directly, such as a missing comma right before that position.
A systematic approach for a larger file
For a large JSON file with an error, working from the reported position outward — checking the immediately surrounding brackets and commas first — is more efficient than reading the entire file from the start, especially since a single missing character early in a file can cause an error to be reported much later in the parsing process.