react项目npm start启动失败（webpack版本冲突问题）

运行了一个别人的react的项目，npm install 安装完依赖之后npm start出现报错，弄了一个中午才弄好，报错的代码如下：

> react_first@0.1.0 start C:\Users\1147484597\Desktop\代码css，js\react\day6react脚手架\react_fir
st
> react-scripts start


There might be a problem with the project dependency tree.
It is likely not a bug in Create React App, but something you need to fix locally.

The react-scripts package provided by Create React App requires a dependency:

  "webpack": "4.44.2"

Don't try to install it manually: your package manager does it automatically.
However, a different version of webpack was detected higher up in the tree:

  C:\Users\1147484597\node_modules\webpack (version: 4.46.0)

Manually installing incompatible versions is known to cause hard-to-debug issues.

If you would prefer to ignore this check, add SKIP_PREFLIGHT_CHECK=true to an .env file in your p
roject.
That will permanently disable this message but you might encounter other issues.

To fix the dependency tree, try following the steps below in the exact order:

  1. Delete package-lock.json (not package.json!) and/or yarn.lock in your project folder.
  2. Delete node_modules in your project folder.
  3. Remove "webpack" from dependencies and/or devDependencies in the package.json file in your p
roject folder.
  4. Run npm install or yarn, depending on the package manager you use.

In most cases, this should be enough to fix the problem.
If this has not helped, there are a few other things you can try:

  5. If you used npm, install yarn (http://yarnpkg.com/) and repeat the above steps with it inste
ad.
     This may help because npm has known issues with package hoisting which may get resolved in f
uture versions.

  6. Check if C:\Users\1147484597\node_modules\webpack is outside your project directory.
     For example, you might have accidentally installed something in your home folder.

  7. Try running npm ls webpack in your project folder.
     This will tell you which other package (apart from the expected react-scripts) installed web
pack.

If nothing else helps, add SKIP_PREFLIGHT_CHECK=true to an .env file in your project.
That would permanently disable this preflight check in case you want to proceed anyway.

P.S. We know this message is long but please read the steps above :-) We hope you find them helpf
ul!

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! react_first@0.1.0 start: `react-scripts start`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the react_first@0.1.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above
.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\1147484597\AppData\Roaming\npm-cache\_logs\2021-05-07T04_44_17_766Z-debug.l
og

根据提示应该是webpack的版本问题，在网上找到了几种解决方案，总结了一下
1.最推荐的一种解决办法：在项目文件夹中新建 .env文件，在文件中添加 SKIP_PREFLIGHT_CHECK=true ，然后在npm start 就ok了

2.先 npm ls webpack 查看冲突的包版本

然后npm install [email protected] 把冲突包安装

最后再使用npm start运行项目

3.把提示的路径的webpack文件夹彻底删除，也可以先剪切一下尝试看能不能，如果除了其他问题再恢复回来，删的话要全局安装webpack新版本，或者指定版本。