"react-virtualized" uses UMD style loading to work in many different environments. It assumes that "react", "react-addons-shallow-compare", and "react-dom" are all included separately via require statements. The paths to our installations are different. If upgrading: - Define the correct paths for React, etc and replace the require statements for the module.exports case with the correct paths. - Replace any references to React.addons.shallowCompare with the webpack module id. - To support use in XUL documents, replace calls to createElement with createElementNS("http://www.w3.org/1999/xhtml", but make sure that you aren't replacing any calls to React.createElement. - Also required for XUL, replace document.head and document.body with document.firstElementChild