The **XAML Hot Reload** feature does not work when debugging on Android devices.

[Calichi]

Type: Bug

The changes are not applied after editing and saving a XAML file, even when pressing the "Fire" button. The .NET Hot Reload output displays No changes were found.

Extension version: 1.0.6
VS Code version: Code 1.90.2 (5437499feb04f7a586f677b155b039bc2b3669eb, 2024-06-18T22:34:26.404Z)
OS version: Windows_NT x64 10.0.22631
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i3-10110U CPU @ 2.10GHz (4 x 2592)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled
Load (avg)	undefined
Memory (System)	7.84GB (1.94GB free)
Process Argv	--crash-reporter-id 19165560-5fd2-482a-994e-35e72cd32781
Screen Reader	no
VM	0%

A/B Experiments

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| VS Bug 2113764

[BretJohnson]

@Calichi - FYI, XAML Hot Reload should work as you type. Saving the file shouldn't be necessary. And the "No changes were found" message actually refers to C# changes, not XAML changes, though we're working on improving that message to make it more explicit. FYI on all that.

As for the core issue here, can you provide more info. If you create a new, simple MAUI project (bring up the command palette / .NET: New Project... / .NET MAUI) does Hot Reload work there? Does it fail for all pages in your app or just some? When it fails, can you please share the contents of the .NET Hot Reload output pane and the Debug Console app output, especially searching for Hot Reload related errors (look for Hot Reload) in the app output.

Thanks. I would like to get this issue tracked down & working, both for you and for others who may run into the same problem, whatever it is.

[Calichi]

@BretJohnson - I am attaching a video divided into two parts of the entire process. The overlay of the mobile device screen is not synchronized with the video, but it was recorded during the demonstration.

bug_hot_reload_part_1.mp4

bug_hot_reload_part_2.mp4

[Calichi]

@BretJohnson - Note also, there is an instruction: ‘Start sdb and execute…’ What is sdb? Could there have been a typo when trying to write adb, or is it some tool that I am unfamiliar with? I have already conducted a search, but I cannot find anything related to it

[BretJohnson]

@BretJohnson - Note also, there is an instruction: ‘Start sdb and execute…’ What is sdb? Could there have been a typo when trying to write adb, or is it some tool that I am unfamiliar with? I have already conducted a search, but I cannot find anything related to it

Where do you see that message? Can you paste the full message or a screenshot maybe?
And thank you for the videos - they are indeed helpful.

[Calichi]

@BretJohnson - The message is located in the yellow-highlighted area, but it is in Spanish.

[BretJohnson]

@BretJohnson - The message is located in the yellow-highlighted area, but it is in Spanish.

Ah, gotcha. Below is the English version of that UI. sdb isn't a typo, it refers to Android debugger technology. Though as I read that message it does seem confusing, it kind of reads like an instruction to the user on something they should do rather than an explanation of what the build/launch process is doing automatically to connect the debugger. I'll create a bug on that, suggesting the message improved. Thanks for pointing it out.

[BretJohnson]

But as for your issue, the Hot Reload initialization error: No HotReload connection specified message in the app launch output indicates a problem. XAML Hot Reload won't work if that message shows up. Now to figure out why - what's going wrong that triggers that.

Can you please try this:

1. cd "C:\Program Files (x86)\Android\android-sdk\platform-tools" (assuming your android sdk is installed there, which it normally is)
2. See what the output of .\adb.exe shell ls -l /data/local/tmp is. There should be an ide-launchenv.txt file in that directory, which is how environment variables, like the one used for the HotReload connect info, get passed to the Android app at launch time. If something went wrong creating that file - perhaps a permission issue with the Android device/emulator in question - that would cause the symptoms you see.

[BretJohnson]

And what kind of Android device is this? It's a physical Android device, not an emulator, right?
Can you try with an emulator image, like say a Pixel 7 emulator, and see if that works.
My guess is that there's some security issue (or possibly a non security device specific issue) that causes using adb to create the /data/local/tmp/ide-launch-env.txt file to fail on that device. If that's the case, I'd like us to handle that scenario better, though I'm not sure how yet. In any case, let's see what you find with the above checks & go from there. Thanks for your help tracking this down.

[Calichi]

@BretJohnson - Indeed, I am using a physical mobile device to debug my applications, and I have no intention of doing so on an emulator. For the same reason, I am seeking assistance. Perhaps you could explain how executing on the emulator could help resolve the issue with the physical device? Or what is their relationship?

It’s worth mentioning that I have debugged on the Windows target, and Hot Reload works perfectly.

Perhaps it’s not relevant, but I usually work with Visual Studio Community, and everything works perfectly there. I wanted to bring my project to VS Code because I heard that it now supports Hot Reload on Android devices, and honestly, it’s more convenient for me to work in VS Code.

Finally, I am fully willing to provide any information you need to help resolve this issue.

[Calichi]

@BretJohnson - This is the result of executing the mentioned command, but on the physical device, not on an emulator. As you can see, the mentioned file appears ide-launch-env.txt. However, it differs slightly in the name. Could this be the cause of the issue?

[BretJohnson]

@Calichi - Thanks for that info. Can you also share the results of running this adb command (with the physical device connected): .\adb.exe shell cat /data/local/tmp/ide-launchenv.txt
And the file name looks correct for you - it should indeed be ide-launchenv.txt. The issue must be something else.

As for running on an emulator, I only mentioned that to better understand what scenarios do & don't work for you, as a troubleshooting step. But you don't need to do it - the adb output above is the most useful. And indeed my goal, as is yours, is figure out why this isn't working for you, with your device, and fix things so it does (probably by making some change in our code, though maybe there's a workaround in advance of that).

Thanks again for your help tracking this down. We're getting closer.

[Calichi]

@BretJohnson

Here's requested execution's result for the given command:

[BretJohnson]

@Calichi Thanks. That looks valid. As the next check do you think you can add a little code to your app to get the value of the RuntimeInformation.OSDescription property, running that on your Android device (like in the debugger) and see what it returns. The current code checks if RuntimeInformation.OSDescription.Contains("android") in order to determine if it's an Android device - if that check returned false for some reason, it would result in the behavior you see. That check may not be exactly right, for all devices, and need to be updated - but we'll see, based on what your device reports. Thanks again.

[Calichi]

@BretJohnson

Here's the result.

[Calichi]

@BretJohnson

More information.

[BretJohnson]

Thanks. So that's the issue. And this device is an OPPO A15 (https://www.oppo.com/en/smartphones/series-a/a15/specs/), right? It looks like the OS there is ColorOS 7.2 based on Android 10, so Android with some customizations. In any case, I'll look to update the code for a better check on whether running on Android, avoiding RuntimeInformation.OSDescription. In the meantime, I can't think of any good workarounds, other than say using an emulator temporarily for Hot Reload. But I'll fix it. We publish weekly pre-release channel updates of the extension. Once the bug here is noted as fix, look for an update published to pre-release there that contains the fix. So you shouldn't have to wait too long. Thanks again very much for your help tracking this down.

[Calichi]

@BretJohnson

You’re welcome! Thank you for your attention and follow-up. I’ll wait for the update

[BretJohnson]

I'll update this issue to mark it fixed, once we have a fix in place & we'll close the issue after the fix is released publicly.

[Calichi]

@BretJohnson

Ok.

I can post another bug about debugging MAUI apps on my Android device, but this one occurs in both VS Code and VS Community.

[BretJohnson]

@BretJohnson

Ok.

I can post another bug about debugging MAUI apps on my Android device, but this one occurs in both VS Code and VS Community.

Sounds good. For issues that happen in both VS Windows and VS Code, I'd suggest reproducing it in VS Windows, then create a feedback ticket (Help / Send Feedback / Report a Problem). Feedback tickets include logs which sometimes help. And note on the feedback ticket that you also see it on VS Code. Reporting a separate VS Code bug here, in addition to the VS Windows feedback ticket, shouldn't normally be necessary, but on the other hand it couldn't hurt and will raise visibility so feel free to do that if you'd prefer.

[Calichi]

Once again, thank you very much!

[ziomek64]

For me XAML hot reload works in emulator but doesn't in real device too

[BretJohnson]

This is fixed, in C# extension version 2.39 (and later), currently published to the pre-release channel.
@Calichi - After updating to the latest prerelease version of the C# extension, if you still see any problems let us know.
@ziomek64 - Same for you. Thanks.

[Calichi]

@BretJohnson

This issue seems to be resolved because I’ve been able to debug on the device. However, hot reload doesn’t load on various occasions during the start of debugging, and it shows me these messages:

Hot Reload initialization error: Launch environment file was last updated 141 seconds ago and is expired
Hot Reload initialization error: No HotReload connection specified