Can't run build of ionic4

"@angular/compiler-cli": "^6.1.8"
"@angular/cli": "^6.1.8"
"@angular/compiler": "^6.1.8"

all 3 same. then why this error?

btw whats the role of www folder in ionic v4 ?

If you have upgraded your angular CLI then your project might still be using angular-cli.json. That file has been replaced with angular.json.

Try running this command before you serve:
ng update @angular/cli --migrate-only

The www folder is generated angular and consists of all files for your website after everything has been transpiled and webpacked.

can u tell me command to run that www folder? i tried few but no luck. i tried ‘serve -p 8080’ and it worked but i want without serve. i have yarn not npm in my machine.

and i tried this