These are the most probable reasons your Create React App (CRA) is not working in Internet Explorer 11 (IE11) IE11 is not included in package.json browserList Promise fails in IE11 fetch function fails in IE11 Fix Update package.json browserList to this (see minimum IE version changed from <=11 to <=10) Add support for fetch Add npm packages whatwg-fetch Add support for Promise and other polyfills Add npm package core-js and regenerator-runtime Update src/index.js with the newly added packages This should work your CRA in IE11.