Unexpected character encountered while parsing number: :. Path '', line L, position N.
This message comes from Newtonsoft.Json JsonConvert on Newtonsoft.Json 13.0.3 on .NET 8.0.30. In this registry it is produced by 1 distinct mistake. Positions in the real message vary with your input; the causes do not.
Causes
What produces this message
Colon inside a JSON array
Input
[1: 2]Exact message: Unexpected character encountered while parsing number: :. Path '', line 1, position 2.
Fix: Decide which you meant: `{"1": 2}` for a mapping, `[1, 2]` for a list.
Same bug, other languages
What other parsers say about the same input
If a colleague reports a different message for what looks like the same file, this is why.
| Parser | Message for the same inputs |
|---|---|
| CPython json.loads | Expecting ',' delimiter: line L column C (char N) |
| Gson | Unterminated array at line L column C path $… |
| Gson JsonParser (lenient off) | Unterminated array at line L column C path $… |
| JSON5 | JSON5: invalid character ':' at 1:3 |
| JSON::PP | , or ] expected while parsing array, at character offset N (before "…") |
| Jackson ObjectMapper | Unexpected character (':' (code 58)): was expecting comma to separate Array entries |
| JavaScriptCore JSON.parse | JSON Parse error: Expected ']' |
| Newtonsoft.Json JsonTextReader | Unexpected character encountered while parsing number: :. Path '', line L, position N. |
| Ruby JSON.parse | unexpected token at '…' |
| SpiderMonkey JSON.parse | JSON.parse: expected ',' or ']' after array element at line L column C of the JSON data |
| System.Text.Json Deserialize | ':' is an invalid end of a number. Expected a delimiter. Path: $ | LineNumber: L | BytePositionInLine: C. |
| System.Text.Json JsonDocument | ':' is an invalid end of a number. Expected a delimiter. LineNumber: L | BytePositionInLine: C. |
| V8 JSON.parse | Expected ',' or ']' after array element in JSON at position N (line L column C) |
| encoding/json Unmarshal | invalid character ':' after array element |
| hjson | End of input while parsing an array (missing ']') at line L,6 |
| json-bigint | Expected ',' instead of ':' |
| json_decode | Syntax error |
| orjson | unexpected character, expected ',' or ']': line L column C (char N) |
| serde_json::from_str | expected `,` or `]` at line L column C |
| ujson | Unexpected character found when decoding array value (2) |
Sources
Standards this registry is checked against
- RFC 8259 (STD 90) — The JavaScript Object Notation (JSON) Data Interchange Format, T. Bray, Ed., 2017. The IETF Internet Standard for JSON. Obsoletes RFC 7159 and RFC 4627.
- ECMA-404, 2nd edition — The JSON Data Interchange Syntax, Ecma International, 2017. Ecma’s grammar for JSON. A normative reference of RFC 8259; the two define the same syntax.
- The Unicode Standard — The Unicode Standard, Core Specification, The Unicode Consortium, current. Normatively referenced by RFC 8259 for the definition of a character.
- IEEE 754-2019 — IEEE Standard for Floating-Point Arithmetic, IEEE, 2019. Referenced by RFC 8259 §6 as the basis for its interoperability guidance on numbers.
Only standards bodies and peer-reviewed venues are cited. Error strings on this site are observed by executing each parser; the standards above define what the parser is reacting to.