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Updated May 29, 20265 min read

Bad Escaped Character in JSON: Valid Escapes and Fixes

A bad escaped character in JSON means a backslash is followed by something JSON does not allow. See the full list of valid escapes, plus fixes for \x, paths, and \u.

SyntaxError: Bad escaped character in JSON at position N means there's a backslash (\) inside a string followed by something JSON doesn't recognize as a valid escape. JSON allows only a small, fixed set of escape sequences — anything else after a \ triggers this error. Here's the full list and how to fix it.

Which string-error am I getting?

What the Error Looks Like

// V8 (Chrome / Node / Edge)
SyntaxError: Bad escaped character in JSON at position 14

// Firefox
SyntaxError: JSON.parse: bad escaped character at line 1 column 15 of the JSON data

// Safari
SyntaxError: JSON Parse error: Invalid escape character \x

The Only Escapes JSON Allows

Inside a JSON string, a backslash may be followed by exactly one of these:

\"   double quote
\\   backslash
\/   forward slash
\b   backspace
\f   form feed
\n   newline
\r   carriage return
\t   tab
\uXXXX   a Unicode code point (exactly 4 hex digits)

Anything else after a \ — \x, \', \a, \0, a Windows path like \Users, or a malformed \u12 — is a "bad escaped character."

Why It Happens

Cause 1 — Borrowing escapes from other languages

// ❌ \x and \' are valid in JS/Python, not in JSON
{ "code": "\x1b[0m", "name": "O\'Brien" }

// ✅ use a \u escape for the byte, and don't escape apostrophes
{ "code": "\u001b[0m", "name": "O'Brien" }

Cause 2 — Windows file paths

// ❌ each backslash starts an invalid escape
{ "path": "C:\Users\Ada\file.json" }

// ✅ escape every backslash (or use forward slashes)
{ "path": "C:\\Users\\Ada\\file.json" }
{ "path": "C:/Users/Ada/file.json" }

Cause 3 — Truncated or malformed \u escape

// ❌ \u needs exactly 4 hex digits
{ "char": "\u12" }

// ✅
{ "char": "\u0012" }

Surrogate Pairs and Non-BMP Characters

JSON's \uXXXX escape is fixed at 4 hex digits, which addresses code points up to U+FFFF (the Basic Multilingual Plane). Characters above that — emoji, many CJK extensions, mathematical symbols — must be written as a UTF-16 surrogate pair:

// 😀 (U+1F600) as a surrogate pair
"\uD83D\uDE00"

// not allowed — JSON has no \U or \u{...}
"\u1F600"     // bad escape (only 4 hex digits consumed; the rest is text)
"\u{1F600}"   // bad escape

This is JSON's encoding in UTF-16 form, even though the file itself is UTF-8 on disk. Two practical consequences:

  • UTF-8 in the file is fine. You can write "😀" literally; modern parsers handle it. The surrogate-pair form is only needed when you must escape.
  • Beware lone surrogates. A \uD83D without its matching low surrogate, or vice-versa, is technically allowed by JSON but is malformed UTF-16 — downstream consumers (especially Postgres jsonb) will reject it. JSON.stringify produces only well-formed pairs.

How to Fix It — Step by Step

  1. Jump to the reported position and find the \ that precedes an invalid character.
  2. Is it a stray backslash? (e.g. a Windows path) — double it to \\, or switch to forward slashes.
  3. Is it a foreign escape like \x or \'? — convert \xNN to \u00NN, and remove the backslash before '.
  4. Is it a short \u? — pad it to exactly four hex digits.
  5. Best fix: build the JSON with JSON.stringify(), which produces only valid escapes.
// Prevention — correct escaping is automatic
JSON.stringify({ path: 'C:\\Users\\Ada', code: '\x1b[0m' });
// → {"path":"C:\\Users\\Ada","code":"\u001b[0m"}

Frequently Asked Questions

What does "Bad escaped character in JSON" mean?

A backslash inside a string is followed by a character that isn't one of JSON's allowed escapes (" \\ / b f n r t or \uXXXX). Common offenders are \x, \', and unescaped Windows paths.

How do I put a Windows path in JSON?

Double every backslash (C:\\\\Users) so each one is a valid \\ escape, or use forward slashes (C:/Users), which JSON accepts.

Is this the same as "Bad control character"?

No. "Bad escaped character" is about an invalid sequence after a backslash; "bad control character" is about a raw, unescaped control byte (tab, newline) with no backslash at all.

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