Unquoted object key in JSON
Object keys must be double-quoted strings. A bare identifier is legal in a JavaScript object literal but not in JSON.
The input
{a: 1}{"a": 1}How to fix it
Wrap every key in double quotes.
This is the giveaway that you are looking at a JavaScript object literal that someone described as 'JSON'. The two are not the same format.
What each parser reports
Every message below was captured by running this exact input through the parser named. 15 of 21 parsers rejected it; 6 accepted it.
| Parser | Exact message |
|---|---|
| CPython json.loads CPython 3.12.3 | Expecting property name enclosed in double quotes: line 1 column 2 (char 1)what this message means → |
| encoding/json Unmarshal Go go1.22.2 | invalid character 'a' looking for beginning of object key stringwhat 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 | Unexpected character ('a' (code 97)): was expecting double-quote to start field namewhat this message means → |
| JavaScriptCore JSON.parse JavaScriptCore (Bun 1.4.1) | JSON Parse error: Expected '}'what this message means → |
| json-bigint Node.js 22.22.2 | Bad string |
| JSON5 Node.js 22.22.2 | accepted — no error |
| JSON::PP Perl 5.038002 | unexpected end of string while parsing JSON string, at character offset 2 (before ": 1}")what this message means → |
| json_decode PHP 8.3.6 | Syntax error |
| 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 character, expected a string key: line 1 column 2 (char 1)what this message means → |
| Ruby JSON.parse Ruby 3.2.3 | unexpected token at '{a: 1}' |
| serde_json::from_str Rust (serde_json 1.x) | key must be a string at line 1 column 2what this message means → |
| SpiderMonkey JSON.parse SpiderMonkey 115 | JSON.parse: expected property name or '}' at line 1 column 2 of the JSON datawhat this message means → |
| System.Text.Json Deserialize .NET 8.0.30 | 'a' is an invalid start of a property name. Expected a '"'. Path: $ | LineNumber: 0 | BytePositionInLine: 1.what this message means → |
| System.Text.Json JsonDocument .NET 8.0.30 | 'a' is an invalid start of a property name. Expected a '"'. LineNumber: 0 | BytePositionInLine: 1.what this message means → |
| ujson CPython 3.12.3 | Expected object or value |
| V8 JSON.parse Node.js 22.22.2 | Expected property name or '}' in JSON at position 1 (line 1 column 2)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 | An object is curly brackets around zero or more members. A name is a string, a single colon separates name from value, and a single comma separates a value from a following name. |
| 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 | Gives the object grammar and states that the syntax does not require name strings to be unique and assigns no significance to member ordering. |
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