create-react-app创建项目报错

create-react-app my-app创建项目时报如下错误

C:\kc\hb\react>npx create-react-app my-app
npx: installed 98 in 7.775s

Creating a new React app in C:\kc\hb\react\my-app.

Installing packages. This might take a couple of minutes.
Installing react, react-dom, and react-scripts with cra-template...

C:\kc\hb\react\my-app>"node"  "C:\Users\liu\AppData\Roaming\npm\\node_modules\yarn\bin\yarn.js" "add" "--exact" "react" "react-dom" "react-scripts" "cra-template" "--cwd" "C:\kc\hb\react\my-app"
yarn add v1.19.1
info No lockfile found.
[1/4] Resolving packages...
error Couldn't find package "react" on the "npm" registry.
info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.
Missing dependencies in package.json

解决办法：

下载yarn

npm uninstall yarn -g

然后重新创建项目 

create-react-app my-app

创建成功

cd my-app 进入项目

npm start 运行项目