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": "4.19.1"

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\17720\node_modules\webpack (version: 4.25.1)

(version: 2.9.1) Manually installing incompatible versions is known to cause hard-to-debug issues.

PS C:\Users\17720\Desktop\Study\React\hello> npm start

> hello@0.1.0 start C:\Users\17720\Desktop\Study\React\hello

> 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": "3.1.14"

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\17720\node_modules\webpack-dev-server (version: 2.9.1)

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

npm un webpack

npm un webpack-cli

npm un webpack-dev-server

npm i webpack@4.19.1

npm i webpack-cli

npm i webpack-dev-server@3.1.14