In this guide
"It installs on my phone but not on the tester's." "The update fails with a signature error." Many of these problems trace back to one thing: the same app can be signed with different keys depending on how the build reaches the device.
The three kinds of build
Local build. You build and install from your computer, usually signed with a debug key or your own key. Nobody else can update it unless they have the same signature.
Upload-signed bundle. You sign your app bundle with your upload key and send it to Google Play. According to Google's Play Console help on Play App Signing, the upload key is held by you and is used so Google can verify your identity.
Play-delivered build. With Play App Signing, Google holds the app signing key and signs the APKs it delivers to users with it. So the build a tester gets from Google Play is signed by a different key than the file you uploaded. (Source: Play Console Help, retrieved 2026-10-23.)
What this breaks, by symptom
- "App not installed" or a signature conflict when updating. The installed copy was signed with one key and the new one with another. A typical case: a tester installed your local APK, then tries the Play test version, or the other way round. Android will not update across different signatures.
- Fix: uninstall the existing copy and install again from one source only. Tell testers which source to use, and warn them that app data is lost on uninstall.
- A sign-in provider or API refuses the app. Services that check your app's signing certificate fingerprint may know only the local or upload key. Builds delivered by Play carry the Play app signing key's certificate, so register that one too. Check each provider's current documentation for where to find and register fingerprints.
- Different behavior between your debug build and the tester's build. Debug builds often differ from release builds in more than the key, such as shrinking and logging. Test the release build that Play delivers.
- Lost key worries. Per the same help page, if you lose or suspect compromise of your upload key, you are not locked out: you create a new one and request a reset in the Play Console. Keep the upload key safe anyway.
A practical rule for test builds
- Pick one distribution path per tester group: either Play test track or direct APK, not both.
- Before a test round, tell testers to remove older copies installed another way.
- Check the fingerprint your services expect and compare it with the build testers actually receive.
- Test the Play-delivered build at least once before release, not only your local one.
What to tell testers
A short note is enough: "Install only from the invite link. If you installed an earlier version from somewhere else, uninstall it first."
Back to the Android app testing hub. Related: language and region testing and camera and media testing.
AppReviewX offers private, structured feedback and test groups for Google Play (12 testers, 14 days in a row, for Android apps). 1 feedback = 1 credit. Start free.
Check the linked Google page before relying on details; key handling can change.