反应脚本 3.4.0 的 npm start 问题

Question

I know this question has already been asked but I can't find a solution. When I run npm start inside a react project, I always get the same logs (see below). The only solution given is to uninstall node_modules and re-do the installation. I also tried to clear the cache. Nothing worked.

Some people solved this problem upgrading to react-scripts 3.4.0 ( https://github.com/facebook/create-react-app/issues/8490 ) but that didn't work for me. The only solution I have now is to downgrade react-scripts to version 2.1.8 by using npm install react-scripts@2.1.8 . But it's not a good solution because I have to work on a framework that uses the latest version.

here are the logs :

i ｢wds｣: Project is running at http://192.168.43.27/
i ｢wds｣: webpack output is served from /
i ｢wds｣: Content not from webpack is served from C:\Users\fthom\Desktop\temp\my-app\public
i ｢wds｣: 404s will fallback to /index.html
Starting the development server...

events.js:288
      throw er; // Unhandled 'error' event
      ^

Error: spawn cmd ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:267:19)
    at onErrorNT (internal/child_process.js:469:16)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)
Emitted 'error' event on ChildProcess instance at:
    at Process.ChildProcess._handle.onexit (internal/child_process.js:273:12)
    at onErrorNT (internal/child_process.js:469:16)
    at processTicksAndRejections (internal/process/task_queues.js:84:21) {
  errno: 'ENOENT',
  code: 'ENOENT',
  syscall: 'spawn cmd',
  path: 'cmd',
  spawnargs: [ '/s', '/c', 'start', '""', '/b', '"http://localhost:3000/"' ]
}
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\fthom\AppData\Roaming\npm-cache\_logs\2020-02-21T10_59_13_574Z-debug.log

Answer 1

I finally found a solution. Add the default variables in the machines PATH:

C:\\Windows\\system32
C:\\Windows
C:\\Windows\\System32\\Wbem

Screenshot of variables location

Answer 2

Changing the path worked for me. Just to add, on the above solution for those who didn't know how to change the path (same as me) and some more details.

Here is my way on how to change environment variables on Windows 10:

• Open the Start Search, type in “env”, and choose “Edit the system environment variables”
• Click the Environment Variables… button.
• Go on system variables and under variables find PATH, mark it and click EDIT .
• On the end of the list add paths - you can simply click on new or on the empty field on the end of list: C:\\Windows\\system32 C:\\Windows C:\\Windows\\System32\\Wbem
• Remember to have the npm paths as well: C:\\Program Files\\nodejs C:\\Users{yourName}\\AppData\\Roaming\\npm
• Set the environment variables as needed.
• The New button adds an additional variable. ...
• Dismiss all of the dialogs by choosing OK . Your changes are saved!
• Restart the computer.

Now it should work!

Answer 3

It took me two days to resolve this issue.

Its because of the incompatibility issue of react-scripts so try installing different versions like:

This worked for me:

npm install --save react-scripts@2.1.8

This one did work for many as they claim:

npm install --save react-scripts@3.3.0

It should work as it did to me after an arduous struggle.

Answer 4

Sometimes on windows, I get the same error message randomly if the npm cache is somehow messed up.

Try to run

npm cache clean --force

Delete the node_modules folder and the package.lock.json file and run npm install afterward.

Answer 5

1. Open the Start Search, type in “env”, and choose “Edit the system environment variables

2. Click the Environment Variables Button.

3. Go on system variables and under variables find PATH, mark it and click EDIT.

4. On the end of the list add paths - you can simply click on new or on the empty field

5. Go to your react app folder then go to node_modules and then go to bin folder and then copy url

6. Paste your url in new path