DFuInstallation File Not Found on MAUI .Net8

[MouratidisA]

Issue Description
I tried to implement the DFU on a .NET MAUI application, but it seems that when I create the DfuInstallation object and call the Start() function the process throws an Exception with a message:
java.io.FileNotFoundException:

To Reproduce
Steps to reproduce the behavior:

1. Create a MAUI project using .Net 8
2. Install the Laerdal.Dfu 1.27.8 NuGet package
3. Create a method to download or retrieve your firmware update file
4. Create the DfuInstallation object and call Start()

Expected behavior
Start and complete the DFU process with the BLE device.

** Support code **
To download the firmware file:

public async Task<bool> DownloadFirmwareFile()
        {
            var sqliteDataService = ServiceHelper.GetService<ISQLiteDataService>();
            try
            {
                //Retrieve firmware file in bytes 
                byte[] fileBytes = await HttpClientService.Instance.GetByteArrayAsync(Constants.GetFirmwareUpdate);

                //Create the file inside Android's cache directory for DFU access
                string outputFilePath;
                if (DeviceInfo.Current.Platform == DevicePlatform.Android)
                {
                    outputFilePath = Path.Combine(FileSystem.Current.CacheDirectory, "app_dfu_package.zip");
                }
                else
                {
                    outputFilePath = Path.Combine(FileSystem.Current.AppDataDirectory, "app_dfu_package.zip");
                }

                await File.WriteAllBytesAsync(outputFilePath, fileBytes);

                //Check if the file exists and update the SelectedFirmwareFile
                var exists = File.Exists(outputFilePath);
                if (!exists)
                {
                    Instance.SelectedFirmwareFile = null;
                    return false;
                }
                else
                {
                        Instance.SelectedFirmwareFile = new FileInfo(outputFilePath);
                        return true;                    
                }
            }
            catch (Exception ex)
            {
               Debug.WriteLine($"Exception in DownloadFirmwareFile: {ex.Message}");
                return false;
            }
        }

Development Environment

Development Tools:

• OS: macOS Sequoia 15.4 (24E248)
• IDE: JetBrains Rider 2024.3.6
• DFU Library Version: Nordic DFU Library 1.27.167

---

Logs

App                      |    File path exists: True  
App                      |    File path used: /data/user/0/com.companyname.appname/cache/app_dfu_package.zip  
App                      |    File exists: True  
DfuBaseService  I  DFU service created. Version: 2.9.0  
DfuBaseService  I  Starting DFU service in foreground  
DfuBaseService  | An exception occurred while opening file  
                               java.io.FileNotFoundException: : open failed: ENOENT (No such file or directory)
                               at libcore.io.IoBridge.open(IoBridge.java:496)
                               at java.io.FileInputStream.<init>(FileInputStream.java:159)
                               at java.io.FileInputStream.<init>(FileInputStream.java:115)
                               at no.nordicsemi.android.dfu.DfuBaseService.openInputStream(DfuBaseService.java:1524)
                               at no.nordicsemi.android.dfu.DfuBaseService.onHandleIntent(DfuBaseService.java:1244)
                               at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:78)
                               at android.os.Handler.dispatchMessage(Handler.java:110)
                               at android.os.Looper.loop(Looper.java:219)
                               at android.os.HandlerThread.run(HandlerThread.java:67)
                               Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
                               at libcore.io.Linux.open(Native Method)
                               at libcore.io.ForwardingOs.open(ForwardingOs.java:167)
                               at libcore.io.BlockGuardOs.open(BlockGuardOs.java:252)
                               at libcore.io.ForwardingOs.open(ForwardingOs.java:167)
                               at android.app.ActivityThread$AndroidOs.open(ActivityThread.java:8464)
                               at libcore.io.IoBridge.open(IoBridge.java:482)
                               at java.io.FileInputStream.<init>(FileInputStream.java:159) 
                               at java.io.FileInputStream.<init>(FileInputStream.java:115) 
                               at no.nordicsemi.android.dfu.DfuBaseService.openInputStream(DfuBaseService.java:1524) 
                               at no.nordicsemi.android.dfu.DfuBaseService.onHandleIntent(DfuBaseService.java:1244) 
                               at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:78) 
                               at android.os.Handler.dispatchMessage(Handler.java:110) 
                               at android.os.Looper.loop(Looper.java:219) 
                               at android.os.HandlerThread.run(HandlerThread.java:67) 

---

Help Needed

If there's anything wrong with the update process, missing steps, or misconfiguration on our side, please point it out.
We’d also appreciate any suggestions or known solutions for this kind of issue.

• Is there something we might be missing?
• Are there any recent changes in the library or platform that could cause this?
• Could this be related to how we handle file paths or permissions?

Thanks in advance for your help and time!

[WanftMoon]

@MouratidisA @framinosona getting the same error. did you find the solution?
I'm Currently porting an app from xamarin which is working.

iOS works while android shows up the following message:

File info 
Name: 89-0-0_0_15-0_0_26.zip 
Size: 94029 bytes 
Last Write: 5/27/2025 3:06:43 PM

[DfuBaseService] DFU service created. Version: 2.9.0
[BluetoothAdapter] BluetoothAdapter() : com.companyname.field
[DfuBaseService] Foreground service disabled. Android Oreo or newer may kill a background service few moments after user closes the application.
[DfuBaseService] Consider enabling foreground service using DfuServiceInitiator#setForeground(boolean)
[DfuBaseService] An exception occurred while opening file
[DfuBaseService] java.io.FileNotFoundException: No files found in the ZIP. Check if the URI provided is valid and the ZIP contains required files on root level, not in a directory.
[DfuBaseService] 	at no.nordicsemi.android.dfu.internal.ArchiveInputStream.parseZip(ArchiveInputStream.java:377)
[DfuBaseService] 	at no.nordicsemi.android.dfu.internal.ArchiveInputStream.<init>(ArchiveInputStream.java:158)
[DfuBaseService] 	at no.nordicsemi.android.dfu.DfuBaseService.openInputStream(DfuBaseService.java:1526)
[DfuBaseService] 	at no.nordicsemi.android.dfu.DfuBaseService.onHandleIntent(DfuBaseService.java:1244)
[DfuBaseService] 	at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:77)
[DfuBaseService] 	at android.os.Handler.dispatchMessage(Handler.java:106)
[DfuBaseService] 	at android.os.Looper.loopOnce(Looper.java:230)
[DfuBaseService] 	at android.os.Looper.loop(Looper.java:319)
[DfuBaseService] 	at android.os.HandlerThread.run(HandlerThread.java:67)
OnDfuStateChanged = Disconnected / Connecting
Dfu state = Disconnected
Error: DeviceOtaDfuViewModel.OnDfuErrorOccured - 4097 / DFU FILE NOT FOUND - System.Exception: 4097 / DFU FILE NOT FOUND
OnDfuErrorOccured = 4097 / DFU FILE NOT FOUND
Dfu error = 4097 / DFU FILE NOT FOUND

[WanftMoon]

K, found the issue. The same code that used to work on xamarin to read the bytes of a resource file and write them to the disk failed on Android. it created a file with the correct size, but with only 0s.
changed to:

// Copy the file to the AppDataDirectory
using FileStream outputStream = File.Create(targetFile);
await inputStream.CopyToAsync(outputStream);

//make sure file exists / dump info for debug
if (File.Exists(outputFilePath))
{
   FileInfo fi = new(outputFilePath);
   Debug.WriteLine($"File info \nName: {fi.Name} \nSize: {fi.Length} bytes \nLast Write: {fi.LastWriteTime}");
   return fi;
}

[BluetoothGatt] onSearchComplete() = Device=XX:XX:XX:XX:CC:56 Status=0
[DfuBaseService] Services discovered
[DfuImpl] Buttonless service without bond sharing found -> SDK 13 or newer
[DfuImpl] Enabling indications...
[BluetoothGatt] setCharacteristicNotification() - uuid: 8ec90003-f315-4f60-9fb8-838830daea50 enable: true
OnDfuStateChanged = Connected / Connecting
Dfu state = Connected
OnDfuStateChanged = Starting / Connected
Dfu state = Starting
[DfuImpl] Sending Enter Bootloader (Op Code = 1)
OnDfuStateChanged = EnablingDfuMode / Starting
Dfu state = EnablingDfuMode

and now it works