TypeError: Cannot read property 'flags' of undefined

Question

After cloning a repo, npm install && ionic cordova build android --prod shows me following error.

TypeError: Cannot read pr         


        

Answer 1

Removing @angular/cli should work for you

if not, change Typescript version to ~2.6.2.

@angular/cli 1.7.3 works with Typescript ~2.6.2 only.

Answer 2

I'm using angular 5 and ionic v3. For me work these changes:

"@types/node": "^9.6.55",
"typescript": "3.7.4",
"@ionic/app-scripts": "3.2.3",

If your are using @angular/cli or @angular-devkit, in my case I had to remove it in order to build with --prod tag properly.

Be sure also to remove your node_modules and do npm cache clean -f, then npm i (maybe will be good also remove your package-lock.json)

Answer 3

Installing angular 9.0.0 solved the problem for me

npm install @angular/cli@9.0.0 -g

it was breaking for angular 9.1.5