JavaScript TypeError - "X" is not a non-null object Last Updated : 15 Jul, 2025 Comments Improve Suggest changes 1 Likes Like Report This JavaScript exception is not a non-null object that occurs if an object is not passed where it is expected. So the null is passed which is not an object and it will not work. Message: TypeError: Invalid descriptor for property {x} (Edge) TypeError: "x" is not a non-null object (Firefox) TypeError: Property description must be an object: "x" (Chrome) TypeError: Invalid value used in weak set (Chrome) Error Type: TypeError Cause of Error: Somewhere in the code an object is expected and is not passed. Automatically null is passed which is not an object and it will not work. The user needs to provide a proper object in the given context. Example 1: In this example, 1 is passed in the given method which is a non-null object, So the error has occurred. JavaScript // 1 is non-null object Object.defineProperty({}, 'prop_name', 1); Output(In Chrome console): TypeError: Property description must be an object: 1 Example 2: In this example, the WeakSet object store object keys, Other types of keys are not accepted. So the error has occurred. JavaScript let var1 = new WeakSet(); var1.add('GFG'); Output(In Chrome console): TypeError: Invalid value used in weak set Create Quiz Comment P PranchalKatiyar Follow 1 Improve P PranchalKatiyar Follow 1 Improve Article Tags : JavaScript Web Technologies JavaScript-Errors Explore JavaScript BasicsIntroduction to JavaScript4 min readVariables and Datatypes in JavaScript6 min readJavaScript Operators5 min readControl Statements in JavaScript4 min readArray & StringJavaScript Arrays7 min readJavaScript Array Methods7 min readJavaScript Strings5 min readJavaScript String Methods9 min readFunction & ObjectFunctions in JavaScript5 min readJavaScript Function Expression3 min readFunction Overloading in JavaScript4 min readObjects in JavaScript4 min readJavaScript Object Constructors4 min readOOPObject Oriented Programming in JavaScript3 min readClasses and Objects in JavaScript4 min readWhat Are Access Modifiers In JavaScript ?5 min readJavaScript Constructor Method7 min readAsynchronous JavaScriptAsynchronous JavaScript2 min readJavaScript Callbacks4 min readJavaScript Promise4 min readEvent Loop in JavaScript4 min readAsync and Await in JavaScript2 min readException HandlingJavascript Error and Exceptional Handling6 min readJavaScript Errors Throw and Try to Catch2 min readHow to create custom errors in JavaScript ?2 min readJavaScript TypeError - Invalid Array.prototype.sort argument1 min readDOMHTML DOM (Document Object Model)8 min readHow to select DOM Elements in JavaScript ?3 min readJavaScript Custom Events4 min readJavaScript addEventListener() with Examples9 min readAdvanced TopicsClosure in JavaScript4 min readJavaScript Hoisting6 min readScope of Variables in JavaScript3 min readJavaScript Higher Order Functions7 min readDebugging in JavaScript4 min read Like