Literal tab inside a JSON string
A raw tab character inside string content. Like a newline, it is a control character and must be escaped.
The input
{"a": "col1 col2"}{"a": "col1\tcol2"}How to fix it
Escape it as `\t`.
Tabs *between* tokens are fine — this only applies inside a string.
What each parser reports
Every message below was captured by running this exact input through the parser named. 13 of 21 parsers rejected it; 8 accepted it.
| Parser | Exact message |
|---|---|
| CPython json.loads CPython 3.12.3 | Invalid control character at: line 1 column 12 (char 11)what this message means → |
| encoding/json Unmarshal Go go1.22.2 | invalid character '\t' in string literalwhat this message means → |
| Gson Java 21.0.12 | accepted — no error |
| Gson JsonParser (lenient off) Java 21.0.12 | accepted — no error |
| hjson Node.js 22.22.2 | accepted — no error |
| Jackson ObjectMapper Java 21.0.12 | Illegal unquoted character ((CTRL-CHAR, code 9)): has to be escaped using backslash to be included in string valuewhat this message means → |
| JavaScriptCore JSON.parse JavaScriptCore (Bun 1.4.1) | JSON Parse error: Unterminated stringwhat this message means → |
| json-bigint Node.js 22.22.2 | accepted — no error |
| JSON5 Node.js 22.22.2 | accepted — no error |
| JSON::PP Perl 5.038002 | invalid character 0x9 encountered while parsing JSON string, at character offset 11 (before "\x{9}col2"}")what this message means → |
| json_decode PHP 8.3.6 | Control character error, possibly incorrectly encoded |
| Newtonsoft.Json JsonConvert Newtonsoft.Json 13.0.3 on .NET 8.0.30 | accepted — no error |
| Newtonsoft.Json JsonTextReader Newtonsoft.Json 13.0.3 on .NET 8.0.30 | accepted — no error |
| orjson CPython 3.12.3 | unexpected control character in string: line 1 column 12 (char 11)what this message means → |
| Ruby JSON.parse Ruby 3.2.3 | unexpected token at '{"a": "col1 col2"}' |
| serde_json::from_str Rust (serde_json 1.x) | control character (\u0000-\u001F) found while parsing a string at line 1 column 12what this message means → |
| SpiderMonkey JSON.parse SpiderMonkey 115 | JSON.parse: bad control character in string literal at line 1 column 12 of the JSON datawhat this message means → |
| System.Text.Json Deserialize .NET 8.0.30 | '0x09' is invalid within a JSON string. The string should be correctly escaped. Path: $ | LineNumber: 0 | BytePositionInLine: 11.what this message means → |
| System.Text.Json JsonDocument .NET 8.0.30 | '0x09' is invalid within a JSON string. The string should be correctly escaped. LineNumber: 0 | BytePositionInLine: 11.what this message means → |
| ujson CPython 3.12.3 | accepted — no error |
| V8 JSON.parse Node.js 22.22.2 | Bad control character in string literal in JSON at position 11 (line 1 column 12)what this message means → |
What the specification says
The exact sections that govern this error. Descriptions are our paraphrase; follow the links for the normative text.
| Body | Section |
|---|---|
| IETF | A string begins and ends with a quotation mark. Any Unicode character may appear between them except the quotation mark, the reverse solidus, and the control characters U+0000 through U+001F, which the section requires to be escaped. It also fixes the escape set and the \uXXXX form. |
| Ecma International | A string is code points wrapped in quotation marks; the quotation mark, reverse solidus and U+0000–U+001F must be escaped. Table 3 fixes the escape sequences. |
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