### Version 2.4.4 ### Reproduction link [https://jsfiddle.net/gloxing/Ltjyjjba/](https://jsfiddle.net/gloxing/Ltjyjjba/) ### Steps to reproduce click button twice, the refs of components will be undefined ### What is expected? the topProgress component show again ### What is actually happening? the refs of component will be undefined --- The behaviour is normal in Vue 2.4.2. <!-- generated by vue-issues. DO NOT REMOVE -->