Unable to run react server and node backend at the same time using concurrently

Question

This is my node backend package json file

"scripts": { "start": "node server", "server":"nodemon server", "client":"npm start --perfix client", "dev":"concurrently "npm run server" "npm run client"" },

This is my react package.json file

  },
  "proxy": "http://localhost:8080/"
}

I have set my PORT variable to 8080 . And when i run npm run dev, i get this error in terminal

[1] node:events:504
[1]       throw er; // Unhandled 'error' event
[1]       ^
[1]
[1] Error: listen EADDRINUSE: address already in use :::8080
[1]     at Server.setupListenHandle [as _listen2] (node:net:1330:16)
[1]     at listenInCluster (node:net:1378:12)
[1]     at Server.listen (node:net:1465:7)
[1]     at Function.listen (C:\xampp\htdocs\node\own\expense\node_modules\express\lib\application.js:635:24)
[1]     at Object.<anonymous> (C:\xampp\htdocs\node\own\expense\server.js:18:5)
[1]     at Module._compile (node:internal/modules/cjs/loader:1103:14)
[1]     at Object.Module._extensions..js (node:internal/modules/cjs/loader:1157:10)
[1]     at Module.load (node:internal/modules/cjs/loader:981:32)
[1]     at Function.Module._load (node:internal/modules/cjs/loader:822:12)
[1]     at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:77:12)
[1] Emitted 'error' event on Server instance at:
[1]     at emitErrorNT (node:net:1357:8)
[1]     at processTicksAndRejections (node:internal/process/task_queues:83:21) {
[1]   code: 'EADDRINUSE',
[1]   errno: -4091,
[1]   syscall: 'listen',
[1]   address: '::',
[1]   port: 8080
[1] }
[1] npm run client exited with code 1

I am trying to run react server and node server at the same time using concurrently. But I am getting the same error even though I tried changing ports many and times and also killed all the processes running on that port. Am i doing anything wrong ?

I have removed all the other code form package.json file from both client and server and only kept related code.

Please let me any way from which i can run both react and node servers from npm run dev command ?