JSON Error: Bad Control Character in String

Q: How do I fix the JSON JSON Error: Bad Control Character in String error?

Escape newlines: Replace all real newline characters inside string values with the two-character sequence \n. In most editors, you can search for a literal newline in regex mode (\n in the search field) and replace with \\n. Escape backslashes: Every backslash in a JSON string must be written as \\. A Windows path like C:\Users must become C:\\Users. Escape tabs: Replace literal tab characters inside strings with \t. Use JSON.stringify() to safely serialize: If you're generating JSON in JavaScript, always use JSON.stringify() rather than building the string manually. It handles all required escape sequences automatically. Validate: Paste the corrected JSON into the JSON Validator. Control character errors are often the only thing blocking a parse once other issues are fixed.

SyntaxError: Bad control character in string literal in JSON at position X

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What Causes This Error?

This error occurs when a JSON string contains a raw control character — a character that must be escaped in JSON strings but wasn't. The most common offenders are actual newline characters (ASCII 10), carriage returns (ASCII 13), and tab characters (ASCII 9) embedded directly in a string. JSON requires these to be written as escape sequences: \n, \r, and \t respectively. Backslashes inside strings must also be doubled: \\.

Common Causes

arrow_rightA real newline character inside a string value (from pressing Enter in a text field)
arrow_rightA Windows path using single backslashes: C:\Users\Alice
arrow_rightA regex pattern with backslashes copied directly into JSON
arrow_rightLogging output that included raw control characters pasted into JSON
arrow_rightAn API response that returned a multi-line string without proper JSON encoding

Example: Broken vs Fixed JSON

cancel Invalid JSON (causes the error)

{
  "message": "Hello
World",
  "path": "C:\Users\Alice\Documents"
}

check_circle Fixed JSON (valid)

{
  "message": "Hello\nWorld",
  "path": "C:\\Users\\Alice\\Documents"
}

Step-by-Step Fix Guide

Escape newlines

Replace all real newline characters inside string values with the two-character sequence \n. In most editors, you can search for a literal newline in regex mode (\n in the search field) and replace with \\n.

Escape backslashes

Every backslash in a JSON string must be written as \\. A Windows path like C:\Users must become C:\\Users.

Escape tabs

Replace literal tab characters inside strings with \t.

Use JSON.stringify() to safely serialize

If you're generating JSON in JavaScript, always use JSON.stringify() rather than building the string manually. It handles all required escape sequences automatically.

Validate

Paste the corrected JSON into the JSON Validator. Control character errors are often the only thing blocking a parse once other issues are fixed.

Fix This Error Instantly

Paste your JSON into the validator to get the exact line number and error description. Then use the JSON Editor to make the fix and re-validate in one workflow.

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