Xamarin : Android : System.UnauthorizedAccessException: Access to the path is denied

I'm trying to download a file and I'm getting System.UnauthorizedAccessException: Access to the path "/storage/emulated/0/Download/test.pdf" is denied. I have set required permission in Android Manifest file.

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

Download Path:

Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryDownloads)
If i use the below path as my download path i can able to download the file. But i cant able to share the PDF file to google drive, drop box or any other System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal)

I am using Xamarin.Forms v2.4.0.282 and Xamarin.Android.Support packages v25.4.0.2.

Note: The code was woking fine when use Xamarin.Forms version 2.3.5.256-pre2 and Xamarin.Android.Support packages v23.3.0
Please suggest your ideas to resolve the issue.

Thanks in Advance.