Getting permission to the external storage (file_provider plugin)

I'm having some problems getting permissions to the external storage on android devices with flutter.

When I try to create a directory in my external storage I get this error (I've changed the directory just for this example. In my own project the directory name is different):

I/flutter (12727): ══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
I/flutter (12727): The following FileSystemException was thrown while handling a gesture:
I/flutter (12727): Creation failed, path = '/storage/emulated/0/com.domain.bundle' (OS Error: Permission denied,
I/flutter (12727): errno = 13)
I/flutter (12727): 

I've already added
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
to the manifest file and rebuild the entire project. What else can I try?

Also just listing all the files in the external storage gives the same permission error.

Hope to hear!

Beside needing to add WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE to your android/app/src/main/AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.xxx.yyy">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
...
</manifest>

You also need Runtime Request Permission, by using simple_permissions package:

import 'package:simple_permissions/simple_permissions.dart';

PermissionStatus permissionResult = await SimplePermissions.requestPermission(Permission. WriteExternalStorage);
if (permissionResult == PermissionStatus.authorized){
  // code of read or write file in external storage (SD card)
}

Note:

1. when running SimplePermissions.requestPermission for the First Time， app will popup a window, you MUST click ALLOW:

to give permission.

2. If you already clicked DENY, then uninstall debug app and re-debug it to install and fix this -> trigger the popup window and give you chance to click ALLOW.

In Android Q, this Error will be resolved by adding the Following Lines in AndroidManifest file:

 <application
      android:requestLegacyExternalStorage="true"