E030Error

Language literal is not valid JSON

A Python/JavaScript literal such as True, None, or undefined was used.

What it means

JSON booleans and null are lowercase: true, false, null. Values copied from Python (True, False, None) or JavaScript (undefined) are not valid JSON.

Example

Invalid

{ "ok": True, "data": None }

Valid

{ "ok": true, "data": null }

How to fix it

Use lowercase true/false, and null instead of None or undefined.

Validate your JSON to see this and every other issue highlighted in one pass.

Diagnostics on this page come from @jsonlint/core, the open-source engine that powers the JSONLint validator. Install it with npm install @jsonlint/core.