javascript - Failed to compile with 1 errors pops up when Vue starts

Question

vue has been successfully introduced, why is this error still reported? I deleted vue2 before and replaced it with vue1.
Error content:

ERROR  Failed to compile with 1 errors                                                                                                                                                                                    

This dependency was not found:

* vue in ./src/main.js

To install it, you can run: npm install --save vue
> Listening at http://localhost:8080

Please solve it~What is the problem

Answer 1

The error message reminds you that you need to install vue and the commands are all written