Unhandled Promise rejection

I am using ionic deploy and after the app downloads about 50% then it gives me the below error message.
I am following https://ionicframework.com/docs/pro/deploy/api/

common.js:252 Wrote files in 0 seconds.
polyfills.js:formatted:4839 Unhandled Promise rejection: FileError {code: 1} ; Zone: ; Task: Promise.then ; Value: FileError {code: 1}code: 1__proto__: Object undefined

Could you please suggest me what i am doing wrong .


I found solution to my own problem … It is that we have to delete build and assets directory under www directory.