Invalid Escape in JSON – Find Bad Backslashes

Local processing

A backslash inside a JSON string must begin a supported escape such as \n, \t, \uXXXX, \", or \\. Raw Windows paths and unsupported sequences can make otherwise readable strings invalid JSON.

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39 chars · 3 lines

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Invalid JSONInvalid escape sequence in string
Line 2Column 15Character 17Found “U”
"path": "C:\Users\Ada\new-folder"
The highlighted character is where JSON parsing stopped.

JSON string escape error

How to diagnose invalid JSON escape sequences

JSON gives backslash a special meaning inside strings. Only defined escapes are allowed, so copied Windows paths, regular expressions, or manually escaped text can fail when a backslash is followed by an unsupported character or an incomplete Unicode sequence. This tool is free to use. No account or payment is required.

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Diagnose the problem

Why this happens

Common escape mistakes in JSON strings

JSON supports a defined set of escapes for quotation marks, backslashes, control characters, and four-hex-digit Unicode escapes. A sequence such as \U or an incomplete \u code is not part of the JSON grammar.

  • Windows paths with single raw backslashes.
  • Regular expressions copied into JSON without escaping backslashes.
  • Incomplete or non-hex Unicode escape sequences.

Raw JSON and JavaScript source need different escaping counts

If JSON text is itself stored inside a JavaScript string, JavaScript consumes one escape layer before JSON.parse sees the text. Debug the raw value passed to JSON.parse rather than counting backslashes only in source code.

Resolve the issue

Fix it step by step

  1. Paste the raw JSON text and inspect the backslash nearest the parser failure.
  2. Replace unsupported raw backslashes with valid JSON escapes, commonly \\ for a literal backslash.
  3. Validate the raw JSON again before embedding it in JavaScript, shell, or another string layer.

Use the solving tool

Recommended solution

Run the focused checker with the failing payload to locate the parser error and inspect the nearby source before changing data.

Open JSON Error Checker

Windows path escape example

A literal backslash in raw JSON must be represented as two backslash characters.

Invalid raw JSON

{
  "path": "C:\Users\Ada"
}

Valid raw JSON

{
  "path": "C:\\Users\\Ada"
}

Common questions

Frequently asked questions

Why are Windows paths often invalid JSON?

A single backslash starts a JSON escape sequence. Literal path separators therefore need to be escaped as two backslash characters in raw JSON text.

What escapes are valid in JSON strings?

JSON supports escaped quote, backslash, slash, backspace, form feed, newline, carriage return, tab, and Unicode escapes written as \u followed by four hexadecimal digits.

Why do I sometimes need four backslashes in JavaScript source?

When JSON text is embedded inside a JavaScript string, one escape layer belongs to JavaScript and another belongs to JSON. Inspect the runtime string passed to JSON.parse to see the actual JSON text.

Debugging a specific JSON issue? Browse JSON troubleshooting.