Ionic-cli: Roboto Font not loaded with --prod build

[JaneDawson]

Description:
Roboto Font is not loaded when building with --prod flag.

Steps to Reproduce:
build app with ionic cordova run android --prod
(I don't know if it's the same with iOS)

Output:

Error messages:

Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-regular.woff Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-regular.ttf Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-medium.woff2 Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-bold.woff2 Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-medium.woff Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-bold.woff Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-medium.ttf Failed to load resource: net::ERR_FILE_NOT_FOUND
file:///android_asset/www/assets/fonts/roboto-bold.ttf Failed to load resource: net::ERR_FILE_NOT_FOUND

My ionic info:

cli packages: 
    @ionic/cli-utils  : 1.13.1
    ionic (Ionic CLI) : 3.13.2

global packages:
    cordova (Cordova CLI) : 7.0.1

local packages:
    @ionic/app-scripts : 3.0.1
    Cordova Platforms  : android 6.2.3 ios 4.4.0
    Ionic Framework    : ionic-angular 3.7.1

System:
    Android SDK Tools : 25.2.5
    Node              : v8.2.1
    npm               : 5.4.2
    OS                : Windows 10

Misc:
    backend : legacy

[justinblake]

I have a temporary fix that worked for me while this is being looked at. I commented out the part in app-scripts where the fonts were being deleted. I know that this is not the best the solution but it did fix the issue temporarily. One small warning when doing this, your app size will be a little larger. When I built my app with the --prod flag before commenting out the delete portion my app was roughly 5mb. After I commented out the portion that deletes the fonts for android my app was 6.4mb but all the errors are gone.

I understand that this is not the best solution but I am no longer seeing all the errors when debugging. I'm sure once this issue is addressed, my app will be able to be built closer to the 5mb size. I have attached a screenshot showing the code that I commented out and in the top left corner you can see where the file is located.

[mhartington]

Temporary work around for now is to add

  "config": {
    "ionic_purge_unused_fonts": false
  },

to your package.json.

We'll fix this in app-scripts since this is where the actual process is run.

[RibesAlexandre]

@mhartington you made my day !

It solved my problem with roboto fonts, thanks !

[MaxusDev]

Well, it will cause this problem in some android devices which doesn't come with roboto font by default.
@ionic/app-scripts/dist/optimization/remove-unused-fonts.js has the following comments and code

// Remove all Roboto fonts. Android already comes with Roboto system
// fonts so shipping our own is unnecessary. Including roboto fonts
// is only useful for PWAs and during development.
fontsRemoved.push('roboto*');

by commenting out fontsRemoved.push('roboto*'); does solve my problem, however I noticed a slight increase in .apk size just as stated by @justinblake