Q:

Typescript error on ionic project version 3 created with current ionic 4(5.4.13) CLI

Here is the error message, after running ionic serve
Typescript Error
Cannot find name 'unknown'.
home/jurr/node_modules/@types/graphql-upload/index.d.ts

I have setup with nvm ( node v12.13.1, npm 6.12.1 ).
I'm trying to start ionic 3 generated app with current CLI:
/home/jurr/.nvm/versions/node/v12.13.1/lib
├── cordova@9.0.0
├── ionic@5.4.13
└── npm@6.12.1

Typescript and ionic version: 
"devDependencies": {
    "@ionic/app-scripts": "3.2.2",
    "typescript": "~2.6.2"
 },

A:

In this case problem was solved by updating typescript version to ^3.2.4:
npm install typescript@3.2.4

