Android 'App not installed': what it means and how to fix it
'App not installed' is Android's entire explanation when an installation fails, and it hides at least five different causes. The most common is a signature conflict: you are installing a version of an app whose signing certificate differs from the copy already on the phone, which Android refuses as a security matter. Behind it come a corrupted or incomplete APK file, insufficient storage, an app built for a newer Android than yours, and installation locations the phone will not accept. The message is useless, so the fix is identifying which refusal you actually got.
What causes it
- A signature mismatch between the new APK and the installed version of the same app.
- A corrupted, partial, or tampered APK file.
- Insufficient free storage for the install to complete.
- The app requires a newer Android version than the phone runs (its minimum SDK is higher).
- Leftover data from a previous uninstall, or an app previously installed for a different user profile.
Fix it, in order
- If you already have the app installed, uninstall it first, then install fresh. This resolves the signature conflict, which is cause number one. Back up the app's data first if it matters, since uninstalling removes it.
- Check your free storage. Installs need the APK's size plus working room. Clear a healthy margin and retry.
- Re-download the APK from its original source. A file that stops mid-download or came from a random mirror is often simply broken. Get it again, from the developer or a reputable store.
- Confirm the app supports your Android version. The app's listing states its minimum Android version. If your phone is older, no install method will succeed, and that refusal is Android protecting you.
- Check for a hidden existing copy. Look in Settings, Apps for the app under all users and in any work profile or second space; a copy there still counts as installed and still conflicts.
- Install to internal storage. If the app or phone defaults to an SD card, move the process to internal storage; card-based installs fail in ways that produce this message.
Only install APKs from sources you trust. The signature system that causes the common conflict exists to stop one party's app being silently replaced by another's build. Sideloading around it with files from file-sharing sites trades that protection away, and 'app not installed' is sometimes Android doing you a favor.
Common questions
Why does it say not installed when the download finished fine? Downloading and installing are separate steps. The error appears in the second step, when Android validates the package: its signature against any existing copy, its integrity, and its requirements against your phone. A perfect download can still fail validation.
If I uninstall the old app to fix this, do I lose my data? Yes, uninstalling removes the app's local data, unless the app syncs to an account or you back it up first. If the data matters and the app still opens, back up or export from inside the app before uninstalling.
Related errors