Xamarin.Android 9.1.101 Preview Release Notes

System Requirements | What's New | Blogs | Open Source


Additional information for the Visual Studio 2019 for Mac Preview: After downloading and running the Visual Studio 2019 for Mac Preview installer, launch the new Visual Studio 2019 for Mac Preview app and switch the updater channel to Xamarin Preview to try the new Xamarin.Android preview version. Note that this will also change the Xamarin.Android and Xamarin.iOS versions used by any existing Visual Studio 2017 for Mac installation.

What's new in this release

Build and deployment performance improvements

This release includes several more improvements to build and deployment times.

  • GitHub PR 2088: Adjust the _CopyIntermediateAssemblies target to replace a couple uses of the Copy task with CopyIfChanged and avoid calling the Touch task. This improved the incremental build time for a test project from roughly 7 seconds to roughly 6.5 seconds.
  • GitHub PR 2124: Add conditions and correct item wildcards for the _CreateAapt2VersionCache target to improve build times in projects configured to use AAPT2.
  • GitHub PR 2129: Split part of the ConvertResourcesCases task into a new ConvertCustomView task to avoid repeating work later in the build. This saves roughly half the time spent in the ConvertResourcesCases task, which can be several seconds or more for an initial clean build.
  • GitHub PR 2148: Properly dispose AssemblyDefinition instances during the BuildApk task. This improved the overall build time for a test project by about 5%.
  • GitHub PR 2162: Move the StripEmbeddedLibraries task to be a linker step to save one pass of loading the assemblies for writing and to avoid redundant work on assemblies that the linker would skip. This improved the combined time of stripping and linking for a test project in the Release configuration from 16.1 seconds to 15.4 seconds.
  • GitHub PR 2168: Remove some redundant work the ResolveAssemblies build task was doing when iterating through assembly metadata.
  • GitHub PR 2174: Combine the CheckTargetFrameworks task into the ResolveAssemblies task to save one pass of reading through assembly metadata.

See also:

  • The Build Performance Results page on the project wiki for additional comparisons and updates about the on-going work to continue to improve performance.
  • The latest numbers from the continuous integration builds.

App performance improvements

  • GitHub PR 1886, GitHub PR 2147: Avoid unnecessary string allocations during app startup.
  • GitHub PR 2008, GitHub PR 2126: Use a faster approach to register managed methods with the Android runtime during app startup.
  • GitHub PR 2025: Slightly reduce the overhead of setting up managed method overrides and callback methods for types in or subclassed from Java bindings.

Preliminary Support for android:extractNativeLibs="false"

Android 6.0 (API level 23) introduced a new way to handle native shared libraries that are packaged as part of APKs. Before that API level, the libraries would always be extracted and placed in the application data directory, consuming extra space on the file system. API level 23 added a new manifest <application> element attribute android:extractNativeLibs to control whether the native libraries are extracted during installation. If the attribute is set to false, then Android 6.0 and higher will skip the extraction step and attempt to load the libraries directly from the APK instead.

Xamarin.Android 9.1.101 adds preliminary compatibility support for this functionality. At the moment, enabling this mode requires a few manual steps:

  • Add the android:extractNativeLibs="false" attribute to the <application> element in the Properties\AndroidManifest.xml file

  • Set the $(AndroidStoreUncompressedFileExtensions) MSBuild property to .so in your .csproj file:

  • Add an android environment file to the project with the following contents:


Removal of armeabi support

Due to the removal of armeabi support in Android NDK r17, Xamarin.Android 9.1.101 no longer supports the armeabi architecture. Projects that have this old ABI selected in the $(AndroidSupportedAbis) MSBuild property will now need to remove it. The newer armeabi-v7a ABI should be used instead. The $(AndroidSupportedAbis) setting can be found in the Advanced section of the Android Options project properties in Visual Studio and the Android Build project properties in Visual Studio for Mac.

Release history

December 04, 2018 - Xamarin.Android

This version is included in the Visual Studio 2019 Preview 1 and Visual Studio 2019 for Mac Preview 1 releases.

Issues Fixed

  • GitHub 1615: AndroidClientHandler did not provide TLS 1.1 or TLS 1.2 support on Android versions 4.1 to 4.4.
  • GitHub 2029, GitHub 2218: Build errors could potentially occur in projects configured to use AAPT2 if they also referenced NuGet packages that provided custom values for $(AndroidResgenExtraArgs).
  • GitHub PR 2108: The built-in list of types, methods, and fields to preserve when linking mscorlib included some redundant and outdated items.
  • GitHub PR 2117: A few build tasks were generating warnings or errors that did not include numbered codes.
  • GitHub 2141: App deployment could fail due to an "INSTALL_FAILED_CONFLICTING_PROVIDER" error when using certain recent Android libraries such as Crashlytics that contain their own AndroidManifest.xml file.
  • GitHub 2143: The Desugar build task did not pass the --classpath_entry option to desugar_deploy.jar, resulting in build errors about missing types when desugaring certain .jar files.
  • GitHub PR 2150: The ConvertResourcesCases and CopyAndConvertResources build tasks contained redundant try/catch blocks.
  • GitHub PR 2187: The CompileToDalvik build task was passing individual input item names on the command line to dx.jar instead of combining the names into a file and using the --input-list option. This could potentially cause issues with command line length limitations in cases where many inputs were given.
  • GitHub 2193: Building, adding a new view to a .axml layout file, and then deploying an application could lead to an "Android.Views.InflateException... Attempt to invoke virtual method on a null object reference" error when running the app because the layout file updates were not deployed as expected.
  • GitHub 2200: Builds could hit a new error in Xamarin.Android 9.1 instead of automatically using the default detected location as expected in projects that had a nonexistent custom path explicitly set in the $(AndroidSdkDirectory) MSBuild property.

Integrated Mono features/fixes

This version of Xamarin.Android currently uses Mono 5.14 Commit 969357ac. The embedded Mono version will be updated in the next Xamarin.Android version 9.1.101 preview.

Known Issues

Due to source branching strategy, this first Xamarin.Android 9.1.101 preview does not yet include the fix for the following issue:

  • GitHub 2205: Android resource conflicts can occur after rebuilds in projects referencing the Xamarin.GooglePlayServices.Basement NuGet package if the projects include a google-services.json file and are configured to use AAPT2.


Your feedback is important to us. If there are any problems with this release, check our GitHub Issues, Xamarin.Android Community Forums and Visual Studio Developer Community for existing issues. For new issues within the Xamarin.Android SDK, please report a GitHub Issue. For general Xamarin.Android experience issues, let us know via the Report a Problem option found in your favorite IDE under Help > Report a Problem.


A big Thank You! to contributors who made improvements in this release:

OSS core

Xamarin.Android 9.1.101 is based on the open-source Xamarin.Android repositories: