How Do You Update an Old Mobile App That Has Not Been Touched for Years?
You update an old mobile app by first auditing it, then rebuilding it with the current Apple and Google development kits, replacing the third-party libraries that have gone stale, and retesting it on current phones before resubmitting it to the stores. How much work that is depends on how long the app has been untouched and on whether you still hold the source code, the store accounts and the signing keys. The first step is always an assessment, not a code change.
Most neglected apps come back to life in one of three ways: a minimum compliance update, a modernization of the existing code, or a rebuild. Entrant Technologies builds and maintains mobile apps, including Android app development and iPhone work, and the guidance below applies to either platform.
What goes out of date in a mobile app that nobody has touched?
Five things age even when the code does not change: the platform version the app was built for, the third-party libraries inside it, its login and payment components, the server APIs it talks to, and its screen layouts.
Apple and Google raise their build requirements regularly, so an app compiled years ago cannot be resubmitted as it is. Third-party SDKs for analytics, maps, advertising and push notifications are retired or changed by their vendors. Login and payment libraries are the most time-sensitive, because providers withdraw old versions for security reasons. Your backend may have moved on, leaving the app calling endpoints due for removal. Layouts designed for older phones can look misaligned on newer screen sizes, foldables and tablets.
What do Apple and Google require before they will accept an update?
Both stores require an update to be built against a recent version of their platform. The figures below are as of October 6, 2026 and are revised periodically.
Apple App Store
Apple's upcoming requirements page states that, since April 28, 2026, apps uploaded to App Store Connect must be built with Xcode 26 or later using an SDK for iOS 26, iPadOS 26, tvOS 26, visionOS 26 or watchOS 26.
Google Play
Google's target API level requirements state that, from August 31, 2026, new apps and app updates must target Android 16 (API level 36) or higher, with lower levels allowed for Wear OS, Android Automotive OS, Android TV and Android XR apps. Apps that sell digital goods have a second deadline: Google's Play Billing Library deprecation page requires version 8 or later for new apps and updates from the same date. Both rules allow an extension request until November 1, 2026.
What happens to an outdated or abandoned app on the stores?
An outdated app is usually hidden from new users or removed from sale; it is not deleted from the phones of people who already have it.
On Google Play, the same target API page says existing apps must target Android 15 (API level 35) or higher to remain available to new users on devices running an Android version higher than the app's target level. People who installed the app earlier can still find, reinstall and use it.
Apple's App Store Improvements page says apps that have not been updated in three years and have had no or extremely few downloads in a rolling 12-month period are flagged for possible removal, and the developer is asked to submit an update within 90 days. Apps that crash on launch are removed immediately. A removed app keeps working for current users and stays in the developer account.
How does a development team assess an old codebase?
A team assesses an old app by trying to build it, listing everything inside it that is out of date, and testing what still works. A typical assessment covers:
- Confirming the source code is complete and matches the version live in the stores.
- Building it with current tools and recording every error.
- Listing each library with its installed version, the current version, and whether the vendor still supports it.
- Checking the backend: which API versions the app calls and whether they are still running.
- Running the live app on current phones to find crashes, layout faults and broken login or payment flows.
- Reviewing the store listing for warnings, privacy declarations and policy notices.
The output should be a written list of findings with an effort estimate for each option, so you can decide with facts.
Should you do a compliance update, modernize the app, or rebuild it?
Choose the smallest option that leaves the app safe to keep running for the period you need it.
Minimum compliance update
The app is rebuilt against the required platform versions and only what breaks is fixed. This suits a stable app with few users or a planned retirement. It does not remove the underlying age, so the same work returns when the requirements next rise.
Modernization
The existing code is kept, but libraries are upgraded, deprecated components replaced, layouts corrected and automated tests added. This suits an app the business depends on whose structure is still sound.
Rebuild
The app is written again, usually reusing the backend and the design. This makes sense when the original framework is no longer maintained, the source code is missing, or the product has changed substantially. A rebuild reopens the technology choice, covered in our comparison of native, Flutter and React Native.
What do you need to hand over to the developers?
You need to hand over the code, access to the store accounts, and the signing keys. Specifically:
- The full source code repository with its history, not a zip of one old version.
- Admin-level access to the Apple Developer account, App Store Connect and Google Play Console, held in the company's name.
- The Android signing keystore and its passwords.
- Access to backend hosting, the database, and API documentation.
- Logins for third-party services: push notifications, analytics, maps, payments, sign-in providers.
Signing keys matter most. Google's Play App Signing documentation says a lost upload key can be reset, but an app signing key that you manage yourself, without Play App Signing, cannot be reset if lost. In that case the app cannot be updated under its existing listing.
What are the common mistakes when updating an old app?
The most common mistake is treating the update as a one-line version change. Raising the target platform version switches on newer privacy, permission and background-activity rules, so features that used to work can fail silently.
Other frequent errors are starting work before confirming that the keys and accounts are available, testing only on new phones and forgetting users on older ones, updating the app without checking the backend it depends on, leaving store privacy declarations unchanged after swapping libraries, and waiting for a removal notice before acting.
What should you do next?
Start by collecting the handover items above and confirming who owns each store account. Then check both consoles for policy notices and deadlines, commission a written assessment, and choose between the three options based on its findings. Once the app is current, schedule a small update at least once a year so it never falls this far behind again.
Quick answers
Can an old mobile app be updated without the original developer?
Yes, an old mobile app can be updated by a new team as long as the owner has the source code, access to the Apple and Google developer accounts, and the Android signing key. Without the source code, the app has to be rebuilt.
Will Apple or Google remove an app that has not been updated?
They can remove it from sale or hide it from new users. As of October 6, 2026, Apple flags apps not updated in three years with very few downloads and gives 90 days to submit an update, and Google Play hides apps below its target API level from new users on newer Android versions.
Do existing users lose an app that is removed from the store?
No. Apple states that a removed app remains fully functional for current users, and Google states that people who previously installed an app can still reinstall and use it.
What Android version must an app update target on Google Play?
As of October 6, 2026, new apps and app updates on Google Play must target Android 16 (API level 36) or higher, with lower levels permitted for Wear OS, Android Automotive OS, Android TV and Android XR apps.
What does Apple require to upload an app update?
As of October 6, 2026, Apple requires apps uploaded to App Store Connect to be built with Xcode 26 or later using an SDK for iOS 26, iPadOS 26, tvOS 26, visionOS 26 or watchOS 26.
Conclusion
The route back for an old app depends on what you still hold and how far the platforms have moved. Gather the code, accounts and keys, get a written assessment, and pick the smallest option that keeps the app compliant for as long as you need it.
If you have an old app and are unsure which option fits, you can contact Entrant Technologies and we will take a look.