in my xamarin Android project everything worked until I have updated to Visual Studio 16.9.0.

Since the upgrade, I am able to successfully build the project but if I try to deploy or debug to device or emulator I receive the following error:

  Adding assembly reference for Xamarin.Firebase.Analytics.Impl, recursively...
  Adding assembly reference for Xamarin.Firebase.Common, recursively...
  Adding assembly reference for Xamarin.Firebase.Iid, recursively...
  Adding assembly reference for Xamarin.Firebase.Iid.Interop, recursively...
  Adding assembly reference for Xamarin.Firebase.Measurement.Connector, recursively...
  Adding assembly reference for Xamarin.Firebase.Messaging, recursively...
  Adding assembly reference for Xamarin.Forms.Core, recursively...
  Adding assembly reference for Xamarin.Forms.Platform.Android, recursively...
  Adding assembly reference for Xamarin.Forms.Platform, recursively...
  Adding assembly reference for Xamarin.Forms.Xaml, recursively...
  Adding assembly reference for Xamarin.Google.Android.Material, recursively...
  Adding assembly reference for Xamarin.Google.AutoValue.Annotations, recursively...
  Adding assembly reference for Xamarin.Google.Guava.ListenableFuture, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Ads.Identifier, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Analytics, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Analytics.Impl, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Base, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Basement, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Location, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Maps, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Measurement.Api, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Measurement.Base, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Places.PlaceReport, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Stats, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.TagManager.V4.Impl, recursively...
  Adding assembly reference for Xamarin.GooglePlayServices.Tasks, recursively...
Skipping target "_CopyConfigFiles" because all output files are up-to-date with respect to the input files.
Skipping target "_ConvertPdbFiles" because all output files are up-to-date with respect to the input files.
Skipping target "_LinkAssembliesNoShrink" because all output files are up-to-date with respect to the input files.
Skipping target "_AndroidXCecilfy" because all output files are up-to-date with respect to the input files.
Skipping target "_GenerateJavaStubs" because all output files are up-to-date with respect to the input files.
Skipping target "_ManifestMerger" because all output files are up-to-date with respect to the input files.
Skipping target "_ConvertCustomView" because all output files are up-to-date with respect to the input files.
Skipping target "_AndroidXJetifyManifest" because all output files are up-to-date with respect to the input files.
Skipping target "_AddStaticResources" because all output files are up-to-date with respect to the input files.
Skipping target "_GeneratePackageManagerJava" because all output files are up-to-date with respect to the input files.
Skipping target "_GenerateAndroidAssetsDir" because all output files are up-to-date with respect to the input files.
Skipping target "_PrepareCreateBaseApk" because all output files are up-to-date with respect to the input files.
Skipping target "_CreateBaseApk" because all output files are up-to-date with respect to the input files.
Skipping target "_CompileJava" because all output files are up-to-date with respect to the input files.
Skipping target "_CompileNativeAssemblySources" because all output files are up-to-date with respect to the input files.
Skipping target "_CreateApplicationSharedLibraries" because all output files are up-to-date with respect to the input files.
Skipping target "_AndroidXJetifyJavaLibraryRules" because all output files are up-to-date with respect to the input files.
Skipping target "_AndroidXJetifyProguardRules" because all output files are up-to-date with respect to the input files.
Skipping target "_CompileToDalvik" because all output files are up-to-date with respect to the input files.
Copying file from "C:temp0androidbincom.caledoslab.runner.apk" to "C:CaledoscodeRunnerCaledosLab.Runner.AndroidbinDebugcom.caledoslab.runner.apk".
Creating "C:temp0android_debug_keystore.flag" because "AlwaysCreate" was specified.
C:Program Files (x86)Androidandroid-sdkbuild-tools.0.2zipalign.exe -p 4 "C:temp0androidbincom.caledoslab.runner.apk" "binDebugcom.caledoslab.runner-Signed.apk" 
C:Program FilesAndroidJdkmicrosoft_dist_openjdk_1.8.0.25binjava.exe -jar "C:Program Files (x86)Microsoft Visual Studio19EnterpriseMSBuildXamarinAndroidapksigner.jar" sign --ks "C:Users
icoldAppDataLocalXamarinMono for Androiddebug.keystore" --ks-pass pass:android --ks-key-alias androiddebugkey --key-pass pass:android --min-sdk-version 21 --max-sdk-version 29  C:CaledoscodeRunnerCaledosLab.Runner.AndroidbinDebugcom.caledoslab.runner-Signed.apk 
Signed android package 'binDebugcom.caledoslab.runner-Signed.apk'
Using cached value from RegisterTaskObject
Found device: emulator-5554

    Command too long

   at Mono.AndroidTools.Adb.AdbClient.GetCommandBuffer(String command) in C:AsExternalandroidtoolsMono.AndroidToolsAdbAdbClient.cs:line 258
   at Mono.AndroidTools.Adb.AdbClient.BeginWriteCommand(String command, AsyncCallback callback, Object state) in C:AsExternalandroidtoolsMono.AndroidToolsAdbAdbClient.cs:line 227
   at Mono.AndroidTools.Adb.AdbClient.BeginWriteCommandWithStatus(String command, AsyncCallback callback, Object state) in C:AsExternalandroidtoolsMono.AndroidToolsAdbAdbClient.cs:line 274
   at System.Threading.Tasks.TaskFactory`1.FromAsyncImpl[TArg1](Func`4 beginMethod, Func`2 endFunction, Action`1 endAction, TArg1 arg1, Object state, TaskCreationOptions creationOptions)
   at Mono.AndroidTools.Internal.AdbClientTaskExtensions.WriteCommandWithStatusAsync(AdbClient client, String command, TaskCreationOptions options) in C:AsExternalandroidtoolsMono.AndroidToolsInternalAdbClientTaskExtensions.cs:line 62
   at Mono.AndroidTools.AndroidDevice.<>c__DisplayClass62_0.<RunShellCommand>b__0(Task t) in C:AsExternalandroidtoolsMono.AndroidToolsAndroidDevice.cs:line 403
   at System.Threading.Tasks.ContinuationResultTaskFromTask`1.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
Done building project "CaledosLab.Runner.Android.csproj" -- FAILED.
Build FAILED.
12>Deployment failed to pixel_3a_xl.
========== Build: 11 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========
========== Deploy: 0 succeeded, 1 failed, 0 skipped ==========

any idea?

thank you!

Source: Visual Studio Questions