/storage/emulated/0/BatchFiles" System.UnauthorizedAccessException: 'Access to the path '/storage/emulated/0/BatchFiles' is denied.

Question

/storage/emulated/0/BatchFiles" System.UnauthorizedAccessException: 'Access to the path '/storage/emulated/0/BatchFiles' is denied.

Anonymous

I get the following error when try to create a file in external storage in a android Xamarin in Visual studio 2022, android version is 12.

/storage/emulated/0/BatchFiles"

System.UnauthorizedAccessException: 'Access to the path '/storage/emulated/0/BatchFiles' is denied.

Anonymous

AndroidManifest.xml file is the below

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.companyname.backupscanningapp" android:installLocation="auto">
	<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="31" />
	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
	<application android:label="Backup Scanning App Lab" android:icon="@drawable/Icon" android:theme="@android:style/Theme.Holo.Light.DarkActionBar">
	</application>
</manifest>

in MainActivity.cs file;

 var filePath = Android.OS.Environment.ExternalStorageDirectory + Java.IO.File.Separator + "MyFiles/Test.csv";

            if (!System.IO.File.Exists(filePath))
            {
                var fileName = Android.OS.Environment.ExternalStorageDirectory + Java.IO.File.Separator + "MyFiles/Test.csv";
                using (var fs = new FileStream(fileName, FileMode.OpenOrCreate))
                    fs.Dispose();

                using (System.IO.StreamWriter batchWriter = new System.IO.StreamWriter(filePath, false))
                    batchWriter.WriteLineAsync("txtRecord");
            }
            else
            {
                using (System.IO.StreamWriter batchWriter = new System.IO.StreamWriter(filePath, true))
                    batchWriter.WriteLineAsync("txtRecord");
            }

Accepted answer

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Your answer

Anonymous

2023-03-28T19:14:51.6566667+00:00

AndroidManifest.xml file is the below

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.companyname.backupscanningapp" android:installLocation="auto"> <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="31" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <application android:label="Backup Scanning App Lab" android:icon="@drawable/Icon" android:theme="@android:style/Theme.Holo.Light.DarkActionBar"> </application> </manifest>

in MainActivity.cs file;

var filePath = Android.OS.Environment.ExternalStorageDirectory + Java.IO.File.Separator + "MyFiles/Test.csv"; if (!System.IO.File.Exists(filePath)) { var fileName = Android.OS.Environment.ExternalStorageDirectory + Java.IO.File.Separator + "MyFiles/Test.csv"; using (var fs = new FileStream(fileName, FileMode.OpenOrCreate)) fs.Dispose(); using (System.IO.StreamWriter batchWriter = new System.IO.StreamWriter(filePath, false)) batchWriter.WriteLineAsync("txtRecord"); } else { using (System.IO.StreamWriter batchWriter = new System.IO.StreamWriter(filePath, true)) batchWriter.WriteLineAsync("txtRecord"); }

Answer 1

Yonglun Liu (Shanghai Wicresoft Co,.Ltd.) 50,126 Microsoft External Staff

Hello,

The reason for this problem is that Google has restricted the program's access to external storage in Android 11 and above, please refer to Storage updates in Android 11.

With this update, your access to external access is limited to the Photo & Media folders, and you can't change the external storage yourself.

In addition to this, you need to request storage permissions at runtime, see the following documentation and examples.

Xamarin.Essentials: Permissions.

var status = Permissions.RequestAsync<Permissions.StorageWrite>();

For Android 11 and above file management, it is more recommended to store files in the internal folder of the program, which can increase security, please refer to Xamarin.Essentials: File System Helpers.

Best Regards,

Alec Liu.

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Anonymous

Alec, thank you for answering my question.

However, I still cannot resolve my issue.

I get error "Access to the path '/storage/emulated/0/MyDirectory' is denied." in my project.

The following are several files in the project.

MainActivity.cs

using Android.App;
using Android.OS;
using Android.Runtime;
using Android.Widget;
using AndroidX.AppCompat.App;
using System;
using System.IO;
using System.Threading.Tasks;
using Xamarin.Essentials;

namespace App12
{
    [Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
    public class MainActivity : AppCompatActivity
    {
        private Button saveButton;
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.activity_main);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            saveButton = FindViewById<Button>(Resource.Id.buttonSaveRec);
            saveButton.Click += SaveButton_Click;

            var status =  CheckAndRequestLocationPermission();

        }
        private void SaveButton_Click(object sender, EventArgs e)
        {
            // Check if external storage is available
            if (Android.OS.Environment.ExternalStorageState == Android.OS.Environment.MediaMounted)
            {
                // Get the path to external storage directory
                var path = Android.OS.Environment.ExternalStorageDirectory.Path;

                // Create a new directory in the external storage
                var directoryName = "MyDirectory";
                var directoryPath = Path.Combine(path, directoryName);
                Directory.CreateDirectory(directoryPath);

                // Create a new file in the directory
                var fileName = "MyFile.txt";
                var filePath = Path.Combine(directoryPath, fileName);

                // Write some text to the file
                using (var streamWriter = new StreamWriter(filePath))
                {
                    streamWriter.Write("Hello World!");
                }

                Toast.MakeText(this, "File saved successfully", ToastLength.Short).Show();
            }
            else
            {
                Toast.MakeText(this, "External storage not available", ToastLength.Short).Show();
            }
        }
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }

        public async Task<PermissionStatus> CheckAndRequestLocationPermission()
        {
            var status = await Permissions.CheckStatusAsync<Permissions.LocationWhenInUse>();

            if (status == PermissionStatus.Granted)
                return status;

            if (status == PermissionStatus.Denied && DeviceInfo.Platform == DevicePlatform.iOS)
            {
                // Prompt the user to turn on in settings
                // On iOS once a permission has been denied it may not be requested again from the application
                return status;
            }

            if (Permissions.ShouldShowRationale<Permissions.LocationWhenInUse>())
            {
                // Prompt the user with additional information as to why the permission is needed
            }

            status = await Permissions.RequestAsync<Permissions.LocationWhenInUse>();

            return status;
        }

    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
	<LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
				<Button
					android:id="@+id/buttonSaveRec"
					android:layout_weight="1"
					android:layout_width="match_parent"
					android:layout_height="75dp"
					android:text="Save Record"
					android:enabled="true" />
		</LinearLayout>
</RelativeLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
          android:versionCode="1" 
          android:versionName="1.0" 
          package="com.companyname.app12">
  <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="33" />
  <application 
    android:allowBackup="true" 
    android:icon="@mipmap/ic_launcher" 
    android:label="@string/app_name" 
    android:roundIcon="@mipmap/ic_launcher_round" 
    android:supportsRtl="true" 
    android:theme="@style/AppTheme"
    android:requestLegacyExternalStorage="true"
    >
  </application>
  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.WRITE_USER_DICTIONARY" />
  <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
  <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
</manifest>

I use Visual Studio 2022.

I would appreciate any help in this matter

Yonglun Liu (Shanghai Wicresoft Co,.Ltd.) 50,126 Reputation points Microsoft External Staff

2023-03-31T02:09:35.7866667+00:00
This is because after Android 11, Google did not allow apps to create folders in external storage:

Starting in Android 11, apps cannot create their own app-specific directory on external storage. To access the directory that the system provides for your app, call getExternalFilesDirs().

Please refer to Storage updates in Android 11 to get more details.

Based on this document, you could use the following code to save your local file to external storage.

var p = GetExternalFilesDir(null); // Create a new directory in the external storage var directoryName = "MyDirectory"; var directoryPath = Path.Combine(p.Path, directoryName);

Anonymous

Yong Lun, thank you for your quick response.

I use the code below

var p = GetExternalFilesDir(null);
                var directoryName = "MyDirectory";
                var directoryPath = Path.Combine(p.Path, directoryName);

                // Create a new file in the directory
                var fileName = "MyFile.txt";
                var filePath = Path.Combine(directoryPath, fileName);

                // Write some text to the file
                using (var streamWriter = new StreamWriter(filePath))
                {
                    streamWriter.Write("Hello World!");
                }

I get the following error;

Could not find a part of the path "/storage/emulated/0/Android/data/com.companyname.app12/files/MyDirectory/MyFile.txt

The emulator I use is Pixel 5 API 30 (Android 11.0 - API 30)

Yonglun Liu (Shanghai Wicresoft Co,.Ltd.) 50,126 Reputation points Microsoft External Staff

2023-04-01T05:17:52.2966667+00:00

This is because the step you took to create the folder was removed.

Please add Directory.CreateDirectory(directoryPath); after var directoryPath = Path.Combine(p.Path, directoryName);.

Or you could delete the MyDirectory path and use the /storage/emulated/0/Android/data/com.companyname.app12/files path provided by Android.
Anonymous

2023-04-03T17:36:11.66+00:00

Yonglun, thank you so much. It seems work since I do not get any exception error.

I want to make sure the file is created. But when I use adb command to access this folder, I get "Permission denied" message.

C:\Temp\App12>adb shell

generic_x86_64_arm64:/ $ cd /storage/emulated/0/Android/data/com.companyname.app12/files/MyDirectory/

/system/bin/sh: cd: /storage/emulated/0/Android/data/com.companyname.app12/files/MyDirectory: Permission denied

2|generic_x86_64_arm64:/ $

How to get access permission to this folder?

Thanks
Yonglun Liu (Shanghai Wicresoft Co,.Ltd.) 50,126 Reputation points Microsoft External Staff

2023-04-04T05:44:46.79+00:00
You need to use the following command to get adb access to your device's external storage.

adb root
Anonymous

2023-06-26T14:11:05.16+00:00

Hi Yonglun,

I have two questions below;

#1 For Android version 11, is it possible to access /storage/emulated/0/ folder, and if yes, how to do it?

#2 For Android version 11, is it possible to access some public storage, and how to do it?

many thanks!

Kevin
Yonglun Liu (Shanghai Wicresoft Co,.Ltd.) 50,126 Reputation points Microsoft External Staff

2023-06-27T03:16:08.3666667+00:00

According to the community rules, it is recommended that you only ask a question in one thread.

To ensure that you receive a clear and helpful answer to your questions, it's important to post them individually. When you have multiple questions, each with its own distinct scenario, it can make it more difficult for the community to understand the problem and provide an accurate solution. For this reason, we recommend that you create separate threads for each of your questions. This way, the community can give you their undivided attention and provide the best possible response.

Therefore, it is recommended that you create the above two questions as new threads.

Answer 2

Anonymous

Thanks Yonglun, it works. I do appreciate your help!

Answer 3

Anonymous

Hi Yonglun,

I understood it. Is it possible to send me a link of your team, I forgot how to submit a question to your team exclusively.

thanks

Kevin

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/storage/emulated/0/BatchFiles" System.UnauthorizedAccessException: 'Access to the path '/storage/emulated/0/BatchFiles' is denied.

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