【问题标题】:React App does not launch and gives errorReact App 无法启动并给出错误
【发布时间】:2021-06-27 16:02:02
【问题描述】:

我尝试从中创建一个反应应用程序,并且我能够从他们提到的设置环境的步骤中创建所有文件和文件夹。但是在运行npm start 命令时,它给出了以下错误:

C:\Users\name\myfirstreact>npm start
$ 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-dev-server": "3.11.1"

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

  C:\Users\name\node_modules\webpack-dev-server (version: 3.11.2)

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-dev-server" 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 C:\Users\name\node_modules\webpack-dev-server is outside your project directory.
     For example, you might have accidentally installed something in your home folder.

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

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!

error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

请帮我解决这个问题,这可能是一个非常愚蠢的问题,但我才刚刚开始学习它,所以基本上我是个菜鸟。

谢谢。

【问题讨论】:

  • 您是否尝试过建议的修复步骤?
  • @AzizaKasenova 是的,我试过了,但 falconFlight 试图告诉我的内容我不清楚。

标签: node.js reactjs npm


【解决方案1】:

您是否尝试过消息中提到的步骤?您是否尝试删除package-lock.json?还是删除 node_modules 并运行npm install

【讨论】:

  • 是的,我按照提示给出的所有内容进行操作。没有成功。
  • 根据 Jose Javier Sanahuja 的回答,尝试在命令中添加 -g 标志并试一试,同时确保将启动脚本更改为 "start:dev": "webpack-dev-server",然后您可以简单地 run npm run start:dev
  • 你能解释一下吗?
  • 好的,所以我想说的是服务器给你一个与"webpack-dev-server": "3.11.1"服务器相关的错误。您是否尝试过在全局范围内添加该软件包,这样您就不会发出另一个命令来启动它?
  • 是的,我试过了。它仍然给出错误。
【解决方案2】:

您是否有可能在全球范围内安装了该依赖项?我的意思是 webpack-dev-server 3.11.2?

检查并删除它或将其替换为以前的

在控制台上试试这个命令。这只是一种预感。它可能无法解决您的问题

npm 卸载 -g webpack-dev-server

【讨论】:

  • 我该怎么做?请不要介意。但我对此真的很陌生。
  • 有 2 或 3 个不同的项目要工作。如果你有一个存货,换另一个。你应该喜欢这个错误,因为在几天之内,你会学到一些新的东西来避免这些错误。试试 npm uninstall -g webpack-dev-server
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