Android external storage

 These permissions need to be declared in the manifest file for external storage in Android. Starting Android 6.0 Marshmallow (API 23), after these permission are declared in the manifest file, they also need to be requested at run time and the user has to grant these in order for the app to access the external storage.

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

On Android 4.4 (API level 19) or higher, your app doesn’t need to request any storage-related permissions to access app-specific directories within external storage. The files stored in these directories are removed when your app is uninstalled.

On devices that run Android 9 (API level 28) or lower, any app can access app-specific files within external storage, provided that the other app has the appropriate storage permissions. To give users more control over their files and to limit file clutter, apps that target Android 10 (API level 29) and higher are given scoped access into external storage called scoped storage, by default. When scoped storage is enabled, apps cannot access the app-specific directories that belong to other apps.

In Android 10, adding android:requestLegacyExternalStorage="true" in the application tag in manifest file can ignore the scoped storage restriction and your apps can still access the external storage like before. With scoped storage enforcement in Android 11 and newer, this flag is not going to work anymore.