Fix emulator boot and deploy flow for `dotnet run` by rmarinho · Pull Request #10969 · dotnet/android

rmarinho · 2026-03-18T18:18:54Z

Summary

Running dotnet run --project <app>.csproj with a stopped Android emulator fails to boot the emulator and deploy the app, producing adb: no devices/emulators found or adb: device '<avd>' not found errors.

This PR fixes two issues in the emulator boot and deploy flow.

Fixes #10965

Problems & Fixes

1. `_EnsureDeviceBooted` not firing during `DeployToDevice`

The .NET SDK's dotnet run invokes DeployToDevice via ProjectInstance.Build(["DeployToDevice"]) in-process. In this execution mode, BeforeTargets hooks are not reliably triggered — only DependsOnTargets chains are respected.

Fix: Add _EnsureDeviceBooted to DeployToDeviceDependsOnTargets in BuildOrder.targets, and to _AndroidComputeRunArgumentsDependsOn in Application.targets, ensuring the emulator boots via the dependency chain during both the main build and the deploy step.

Note: A related issue where Device was not passed as a global property to the deploy step was fixed in the .NET SDK (dotnet/sdk#53018).

2. `adb emu avd name` returns empty on modern emulators

GetRunningAvdName used adb -s <serial> emu avd name to match running emulators to AVD names. On modern Android emulators (tested with emulator 36.4.10), this command returns zero bytes, causing the match to fail even when the correct emulator is already running.

Fix: Try adb shell getprop ro.boot.qemu.avd_name first (always set on emulators), falling back to emu avd name for older emulator versions.

Changes

Microsoft.Android.Sdk.Application.targets — Added _EnsureDeviceBooted to _AndroidComputeRunArgumentsDependsOn, simplified BeforeTargets to just _GetPrimaryCpuAbi (commercial builds), updated comments
Microsoft.Android.Sdk.BuildOrder.targets — Added _EnsureDeviceBooted to both DeployToDeviceDependsOnTargets variants
BootAndroidEmulator.cs — Fixed AVD name detection (getprop ro.boot.qemu.avd_name first, fallback to emu avd name)
BuildOrderTests.cs — Added DeployToDeviceDependsOn_ContainsEnsureDeviceBooted test

Testing

Unit test: DeployToDeviceDependsOn_ContainsEnsureDeviceBooted validates the target chain
Manual E2E: Verified on macOS with emulator 36.4.10, AVD MAUI_Emulator_API_36 (API 36), .NET 11 preview — emulator boots from cold, app deploys and launches with logcat streaming

jonathanpeppers

The problem on the description sounds like:

dotnet/sdk@07d7aa4

Which should be in main, if you have at least:

287f27d

Copilot

Pull request overview

Fixes dotnet run --project <app>.csproj deploy failures when the selected Android emulator is stopped by ensuring the emulator-boot target runs via DependsOnTargets, and improving emulator detection/boot polling in the BootAndroidEmulator MSBuild task.

Changes:

Add _EnsureDeviceBooted into DeployToDeviceDependsOnTargets and _AndroidComputeRunArgumentsDependsOn so it runs reliably during in-proc ProjectInstance.Build(["DeployToDevice"]).
Improve AVD name detection by preferring adb shell getprop ro.boot.qemu.avd_name, with fallback to adb emu avd name.
Handle macOS emulator launcher “fork then exit 0” behavior by continuing to poll adb devices on exit code 0.
Add a unit test asserting _EnsureDeviceBooted is included in DeployToDeviceDependsOnTargets.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.Application.targets	Ensures `_EnsureDeviceBooted` participates in run-argument computation and clarifies execution rationale.
src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.BuildOrder.targets	Adds `_EnsureDeviceBooted` to deploy dependency chains (fast deploy + non-fast deploy).
src/Xamarin.Android.Build.Tasks/Tasks/BootAndroidEmulator.cs	Updates AVD name detection and improves macOS emulator process exit handling.
src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildOrderTests.cs	Adds coverage to validate deploy dependency chain includes `_EnsureDeviceBooted`.

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src/Xamarin.Android.Build.Tasks/Tasks/BootAndroidEmulator.cs

 			if (outputLines.Count > 0) {
-				var name = outputLines [0].Trim ();
-				if (!name.IsNullOrEmpty () && !name.Equals ("OK", StringComparison.OrdinalIgnoreCase)) {
-					avdName = name;
+				var consoleName = outputLines [0].Trim ();
+				if (!consoleName.IsNullOrEmpty () && !consoleName.Equals ("OK", StringComparison.OrdinalIgnoreCase)) {
+					avdName = consoleName;


src/Xamarin.Android.Build.Tasks/Tasks/BootAndroidEmulator.cs

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildOrderTests.cs

Address multiple issues preventing 'dotnet run --project' from successfully booting an Android emulator and deploying the app. Fixes: #10965 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Add init.svc.bootanim check to WaitForFullBoot so we wait for the boot animation to stop before considering the emulator ready - Detect 'used by another emulator' from stderr and fail fast with a clear error instead of silently timing out after 300 seconds - Upgrade key milestone log messages to MessageImportance.High so users see progress during emulator boot (appeared online, system boot complete, fully ready) with elapsed times Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The dotnet/sdk fix (dotnet/sdk#53018) now properly passes the Device global property to DeployToDevice via InvalidateGlobalProperties. Remove the device.props write/read cache that was working around this. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove non-essential improvements (AVD lock detection, offline detection, boot animation check, log message changes) to keep the diff minimal. Only the three actual bug fixes remain: getprop AVD detection, fork handling, and error reporting for non-zero exit codes. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The emulator is already booted by ComputeAvailableDevices before _EnsureDeviceBooted runs, so the task never launches a new emulator process and the fork issue doesn't apply. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The DeployToDeviceDependsOnTargets property expands to multiple log lines because it includes $(_MinimalSignAndroidPackageDependsOn). The test was only checking the first line, which never contained _EnsureDeviceBooted. Switch to MSBuild property functions (Contains/IndexOf) to validate directly in MSBuild, avoiding log parsing entirely. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Keep the readable log-parsing approach (fixed by joining all output lines for multi-line property matching) and add a separate MSBuild property function test as a safety net. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jonathanpeppers reviewed Mar 18, 2026

View reviewed changes

rmarinho marked this pull request as ready for review March 18, 2026 20:37

rmarinho requested review from grendello and simonrozsival as code owners March 18, 2026 20:37

Copilot AI review requested due to automatic review settings March 18, 2026 20:37

Copilot AI reviewed Mar 18, 2026

View reviewed changes

rmarinho force-pushed the dev/ensure-device-booted-deploy branch 2 times, most recently from aa3f844 to d188a4b Compare March 19, 2026 16:27

rmarinho mentioned this pull request Mar 19, 2026

Update copilot-instructions.md with learnings from recent PRs #10974

Open

rmarinho force-pushed the dev/ensure-device-booted-deploy branch from cf51ffd to 62a458e Compare March 19, 2026 18:40

rmarinho and others added 7 commits March 19, 2026 22:45

Fix emulator boot and deploy flow for 'dotnet run'

c523f1b

Address multiple issues preventing 'dotnet run --project' from successfully booting an Android emulator and deploying the app. Fixes: #10965 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Rename name2 to consoleName for clarity

a99d2d8

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

rmarinho force-pushed the dev/ensure-device-booted-deploy branch from 62a458e to a2787ca Compare March 19, 2026 22:45

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Fix emulator boot and deploy flow for `dotnet run`#10969

Fix emulator boot and deploy flow for `dotnet run`#10969
rmarinho wants to merge 8 commits intomainfrom
dev/ensure-device-booted-deploy

rmarinho commented Mar 18, 2026 •

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rmarinho commented Mar 18, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Problems & Fixes

1. _EnsureDeviceBooted not firing during DeployToDevice

2. adb emu avd name returns empty on modern emulators

Changes

Testing

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Pull request overview

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rmarinho commented Mar 18, 2026 •

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1. `_EnsureDeviceBooted` not firing during `DeployToDevice`

2. `adb emu avd name` returns empty on modern emulators