react项目npm start启动失败（webpack问题）

有一段时间没有编写react项目了，编写都是使用以前配置好的环境，从新搭建项目出现的问题，在网上找了找解决方法，

不是特别理想吧，有的就是在提问这个问题，有一个是添加文件，处理问题，但是不是太确定，好不好。先看下报错信息是否相似吧。

报错信息如下

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": "4.41.0"

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:

  D:\node\node_modules\webpack (version: 4.16.2)

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 project.
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 project 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 instead.
     This may help because npm has known issues with package hoisting which may get resolved in future versions.

  6. Check if D:\node\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 webpack.

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 helpful!

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! my-app@0.1.0 start: `react-scripts start`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the my-app@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\***\AppData\Roaming\npm-cache\_logs\2019-10-13T00_57_46_532Z-debug.log

其实可能问题也有不同之处吧，但是还是应该有和我问题类似的问题，他报错就是相当于两个版本的问题。

可能你原有版本和现有冲突不兼容所导致，所以说要不然更改，要不然用新替换，但是替换完成之后还是不行，

所以最后把提示的路径的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（注：本人这个问题删除之后，npm start启动成功）删的话要全局安装webpack新版本，或者指定版本哦