Error: Failed to fetch platform cordova-android

Ionic Framework ionic-v3
1

I’ve got this problem:


    allart@allart-vm-lubuntu:~/Documents/apps/MyApp/myapp$ ionic cordova platform add android 
    > cordova platform add android --save
    Using cordova-fetch for cordova-android@^6.2.3
    
    Error: Failed to fetch platform cordova-android@^6.2.3
    Probably this is either a connection problem, or platform spec is incorrect.
    Check your connection and platform name/version/URL.
    Error: npm: Command failed with exit code 1 Error output:
    npm ERR! Linux 4.13.0-16-generic
    npm ERR! argv "/usr/local/bin/node" "/home/allart/Documenti/apps/MyApp/myapp/node_modules/.bin/npm" "install" "cordova-android@^6.2.3" "--production" "--save-exact"
    npm ERR! node v9.2.0
    npm ERR! npm  v2.15.12
    npm ERR! code EPEERINVALID
    
    npm ERR! peerinvalid The package @ionic-native/core@4.4.2 does not satisfy its siblings' peerDependencies requirements!
    npm ERR! peerinvalid Peer @ionic-native/camera@4.4.2 wants @ionic-native/core@^4.2.0
    npm ERR! peerinvalid Peer @ionic-native/facebook@4.4.2 wants @ionic-native/core@^4.2.0
    npm ERR! peerinvalid Peer @ionic-native/file@4.4.2 wants @ionic-native/core@^4.2.0
    npm ERR! peerinvalid Peer @ionic-native/file-path@4.4.2 wants @ionic-native/core@^4.2.0
    npm ERR! peerinvalid Peer @ionic-native/in-app-browser@4.4.2 wants @ionic-native/core@^4.2.0
    npm ERR! peerinvalid Peer @ionic-native/splash-screen@3.12.1 wants @ionic-native/core@^3.6.0
    npm ERR! peerinvalid Peer @ionic-native/sqlite@4.4.2 wants @ionic-native/core@^4.2.0
    npm ERR! peerinvalid Peer @ionic-native/status-bar@3.12.1 wants @ionic-native/core@^3.6.0
    npm ERR! peerinvalid Peer @ionic-native/transfer@3.14.0 wants @ionic-native/core@^3.6.0
    
    npm ERR! Please include the following file with any support request:
    npm ERR!     /home/allart/Documenti/apps/MyApp/myapp/npm-debug.log
    
    [ERROR] Exception:

Already tried with npm cache clean, uninstalling and reinstalling packages and managers, rebooting, upgrading system and so on.

Here are my specs:

  $ node -v
    v9.2.0
    
    $ npm -v
    3.10.10
    
    $ ionic -v
    3.18.0
    
    $ cordova -v
    7.1.0

    Ubuntu 17.10 on a VM.

Any ideas? Thank you in advance.