Reactstrap and React 16

by Brandon Istenes

Starting a new NextJS project, I was getting errors like

TypeError: Cannot read property 'toLowerCase' of undefined
  at ReactDOMServerRenderer.renderDOM (/Users/bistenes/Code/project/node_modules/react-dom/cjs/react-dom-server.node.development.js:2776:27)

and

Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in.

which were obviously totally irrelevant to the actual problem. Turns out Reactstrap <5.0 is incompatable with React 16.

npm i --save reactstrap@next fixed it.