### Version 2.6.10 ### Reproduction link [https://jsfiddle.net/zs5dan7x/](https://jsfiddle.net/zs5dan7x/) ### Steps to reproduce - pass a Symbol as the value of a component prop which expects another type ### What is expected? the console should show the validation error message ### What is actually happening? the prop validator tries to build an validation error message, it fails with : TypeError: Cannot convert a Symbol value to a string <!-- generated by vue-issues. DO NOT REMOVE -->