Failed to fetch platform cordova-android@~6.3.0

Deleted platform and plugins and did cordova prepare. Got following error:

Error: Failed to fetch platform cordova-android@~6.3.0
Probably this is either a connection problem, or platform spec is incorrect.
Check your connection and platform name/version/URL.
Failed to get absolute path to installed module

It works fine when adding individual platform: cordova platform add android
I have cordova 7.1.0 and it says "Platforms and plugins are now required to have a package.json file" but I don't get package.json file created for platforms when adding platforms. is that a problem too?