fastlane supply "Package not found" for the app in CI

Google Play could not find an app for the package name supply sent. Either the applicationId is misspelled, or the very first release has not been made through the Play Console, so the API has no app to act on yet.

What this error means

supply fails with "Google Api Error: notFound: Package not found: com.example.app" or "The product was not found". Authentication succeeded; the app reference did not resolve.

fastlane supply

[!] Google Api Error: notFound: Package not found: com.example.app. - Package not
found: com.example.app.

Common causes

The first APK/AAB was never uploaded manually

Google Play requires the first upload for a brand new app to be done in the Play Console UI. Until then, the Developer API reports the package as not found.

The package_name does not match the applicationId

A typo or the wrong applicationId means supply queries a package that does not exist on this account.

How to fix it

Make the first release in the Console

Create the app and upload the first AAB in the Play Console UI once.
Confirm the exact applicationId in the listing.
Then let supply handle subsequent uploads.

Pass the exact package_name

Match package_name to the applicationId in app/build.gradle exactly, including suffixes.

Terminal

fastlane supply --package_name com.example.app \
  --json_key google-play-key.json --aab app-release.aab --track internal

How to prevent it

Do the first upload of a new app in the Console before automating.
Keep package_name identical to the applicationId, suffixes included.
Confirm the service account can see the app in the Console.