Debugging log · App Bundle

My app shipped in English only — and the translations were right there

This one cost me the better part of two days, so I'm writing it down. I had an app fully translated across a dozen languages. Every res/values-xx folder was in place, the strings were correct, and on my own phone in debug it switched languages perfectly. Then I released the App Bundle, changed my phone to Korean, installed from the Play track — and got English. Not a fallback here and there. Everything, in English.

What I wasted time on first

Because it worked in debug, my instinct was that the translations themselves were broken. They weren't. Here's what I checked that turned out to be fine — so you can skip it:

• The values-xx folders. All present, correctly named, no typos in the locale qualifiers.
• The device locale. The phone really was set to another language; other apps localized correctly.
• Missing keys. Every string existed in every language file. This wasn't a per-string fallback.
• Debug builds. A debug APK installs every resource at once, so it localizes fine — which is exactly why the bug hides until you go through a bundle.

That last point is the trap. A debug build is a single APK with all languages inside, so it can never reproduce the problem. The bug only appears once Play takes your .aab and splits it.

The actual cause: per-language splitting

An Android App Bundle isn't what lands on the user's device. Play generates split APKs from it and delivers only the ones the device needs — including a language split that ships just the device-locale strings to keep the download small. In theory the right language arrives; in practice, if that split doesn't get applied the way you expect, the device is left with only the base resources, which for most of us means English.

The fix: turn language splitting off

The reliable fix is to tell the bundle not to split by language, so every translation is packaged together. In your module's build.gradle:

android {
    bundle {
        language {
            // Don't split by language — ship every locale in the base
            enableSplit = false
        }
    }
}

After this, the released build carries all languages and localizes correctly regardless of how Play assembles the splits. The trade-off is a slightly larger download, since users get every language instead of just theirs. For an app with normal-sized string files that difference is tiny, and correct localization is worth far more than a few kilobytes.

One more thing that bit me: resource shrinking

While chasing this I also hit resource stripping removing localized resources it thought were unused. If you're minifying, make sure shrinking isn't eating your translations. Building with minifyEnabled false confirmed the strings survived; if you keep minification on, verify your keep rules so localized resources aren't dropped.

How to verify before you ship again

Don't trust a debug build here. Reproduce the real delivery instead:

• Upload to an internal or closed testing track and install through Play, then switch your device language. That's the true end-to-end test.
• Or generate the split APKs locally from your .aab with bundletool and install the set, so you exercise the same splitting Play does — not a single universal APK, which papers over the bug.

This is the war-story version. For the tight, copy-paste reference, see the companion guide below.