The Xamarin.Android 5.1 series provides improved support for Android Wear apps.

Note: Xamarin.Android 5.1 requires JDK 1.7 to use Android Wear and API-21. JDK 1.6 may be used when targeting previous API levels.

Please see the separate Xamarin.Android 5.1.7 release notes for API diffs.

• 31705: Embedded resources are not being fast deployed from the IDE in XA 5.1.4+
• 32025: Android library assets in subfolders not added to apk.
• 33554: monodroid error XA0000: Reason: An element with the same key already exists in the dictionary

Xamarin.Android uses Mono 4.0 commit 5ab4c0d0.

• 28777: GZipStream (DeflateStreamNative) native exception after Flush() with no buffer data: Internal error (no progress possible) Flush
• 30043: Disposing a FileSystemWatcher object causes ArgumentOutOfRangeException
• 30868: ObjectDisposedException in mono 4.0.1.28, but not mono 3.12.1
• 30869: HttpClient authentication not working

Xamarin.Android 5.1.5 improves reliability and stability, and adds bindings for Android v5.1 (API-22).

• 28114: Fatal signal 6 (SIGABRT) if Keyboard.CreateKeyFromXml() is overriden.
• 28721: aapt error item with same key
• 29571: Custom [Preserve] attribute only works under the Android.Runtime namespace on Android
• 30823: Aot task fails when the linker is disabled
• 31527: Unable to load file or assembly System.Runtime in project with both shared runtime and Link SDK enabled.
• 31597: Xamarin.Android Breakpoints in certain projects no longer work after upgrading to 5.1.4.

Xamarin.Android uses Mono 4.0 commit 5f447f9d.

• 26205: System.IO.Package.LoadRelationships throws NullReferenceException for some NuGet packages with PCLs generated on Windows.

• Various AOT-related fixes.
• 29130: Fix loading of libmonosgen-2.0.so when loading the shared runtime within a Release build.
• 29939: Fix build error when building android application which references a file with an UPPER_CASE letter in styles.xml.
• 30318, Xamarin.Android Breakpoints in Forms PCL project do not work after cleaning solution, redeploying, and restarting debugging.
• 30670, 30827: Support binding Java libraries with package names that end in .system.
• 30823: Support AOT compilation when linking is disabled.

Xamarin.Android uses Mono 4.0 commit 046a4260.

• Fixes TimeZoneInfo.IsDaylightSavingTime returning false when TimeZoneInfo.SupportsDaylightSavingTime was set to false because the TimeZoneInfo was created with no AdjustmentRules.

• 28747: Nexus 9 sample apps crashing on launch.

• 28961: Avoid duplicate plt symbols for plt entries for synchronized methods.

• 29935: XAttribute.ToString() outputs wrong result if attribute contains namespace.

• 30653, 30555, 30562: Check for new Build-tools 23.0.0_rc1 location of aapt.
• 30566: Creating Java.Lang.String instances on the Android-M preview results in an UnsupportedOperationException: Use StringFactory instead. (Related Android bug)

Xamarin.Android uses Mono 4.0 commit ed1d3ec5.

• 29667: Mono v4.0 crashes after a while.
• 30171: BinaryReader.ReadChar() returns incorrect result on 8.10

• Improve legacy type name fixing within AndroidManifest.xml.
• 28198: LinkAssemblies task failed with a NotImplementedException.
• 29263: android.view.InflateException when defining a custom preference .
• 29568: Android 5.1 AppCompat 22.1.1 unable to find theme resources.

Xamarin.Android uses Mono 4.0 commit d7f9ffaa.

• 26998: Issue with DataContractJsonSerializer.
• 29039: CultureInfo.GetCultures(CultureTypes.SpecificCultures) returns broken ar-SA culture.
• 29177: Check SP on thread suspend correctly.

Xamarin.Android uses Mono 4.0 commit d5e006eb.

• 29570: decimal comparisons look to be broken.

• Simpler Android Wear support.
• 64-bit runtime support.
• System app support.
• Proguard support.
• Multi-Dex support.
• GC-free method invocations.
• AppDomain.UnhandledException event raised for Java exceptions
• OpenGLES 3.1 Support
• New tool, logcat-parse, for investigating GREF use.
• F# bumped to 3.1.1.31.
• New $(JavacTargetVersion) and $(JavacSourceVersion) MSBuild properties can control the javac -target and javac -source values.
• New debug.mono.max_grefc system property, allows overriding the default detected maximum GREF count value.

Previously, Android Wear apps were supported, but required lots of extra manual intervention in order to follow the Android Wear app structure and the manual packaging instructions:

1. Ensure that your Wearable project and Handheld projects had the same version number and package name.
2. Manually build the Wearable project as a Release build
3. Manually add (2) into the Resources\raw directory of the Handheld project.
4. Manually write an XML blob within the Handheld project which refers to (3).
5. Manually add a <meta-data/> element to the Handheld project's AndroidManifest.xml.

Starting in Xamarin.Android 5.0, there is a new, simpler, workflow:

1. Add the Wear project as a Project Reference to the Handheld project.

This will automatically package the Wear app and include it as a resource when building the Handheld project.

The package name of the Wear project and the Handheld project must have the same package name. If they don't, then an XA5304 error will be reported.

Proguard is used to link Java bytecode, allowing .apk files to be smaller.

Proguard support can be enabled by using the new $(EnableProguard) MSBuild property, which is also available via Visual Studio and Xamarin Studio.

Additionally, a new @(ProguardConfiguration) Build action has been added. Files with a Build action of @(ProguardConfiguration) are used as values to the proguard -include option.

The contents of a @(ProguardConfiguration) file contain additional proguard options.

Android apps may have at most 65k methods within the .apk. Multi-dex is a way to increase this method limit.

Multi-dex support can be enabled by using the new $(AndroidEnableMultiDex) MSBuild property, which is also available via Visual Studio and Xamarin Studio.

In previous versions of Xamarin.Android, when invoking Java methods that had one or more parameters, a JNIEnv method would be invoked with a params JValue[] parameter. This resulted in array allocations on every such method invocation, increasing GC allocations and memory pressure.

Starting with Xamarin.Android 5.1, there are new JNIEnv method overloads which instead take a JValue* (unsafe pointer), and the bindings have been updated to make use of the new overloads instead of using the previous params JValue[] overload.

Existing Java library bindings must be rebuilt to make use of the new methods, and Java library bindings built against Xamarin.Android 5.1 will not be usable in previous versions.

In previous versions of Xamarin.Android, the AppDomain.UnhandledException event would only be raised for exceptions thrown from managed code, and not for unhandled Java exceptions thrown on Java threads.

Starting with Xamarin.Android 5.1, the AppDomain.UnhandledException event should be raised for any and all unhandled exceptions, whether raised from managed code or from Java code.

• 64-bit Runtime Support
• AOT Support

Xamarin.Android now provides runtimes for arm64-v8a and x86_64. This allows Xamarin.Android apps to run as 64-bit apps on supported hardware.

Note: 64-bit runtimes are not required in order to run on 64-bit hardware. 64-bit devices such as the Nexus 9 are capable of running 32-bit processes as well. 64-bit runtimes merely allow the process to access more memory, as long as Android grants access to it.

Xamarin.Android now supports Ahead-of-Time (AOT) compilation of assemblies, allowing some JIT overhead to be avoided. This can result in shorter startup times, at the cost of increased .apk sizes.

AOT may be enabled by using the new $(AotAssemblies) MSBuild property, and the LLVM Optimizing Compiler may be used by enabling the new $(EnableLLVM) MSBuild property, both of which will be available via Visual Studio and Xamarin Studio.

TODO: Table comparing startup times, .apk sizes.

Unfortunately, AOT support is experimental at the moment:

• LLVM can't be used when building for x86_64, because of an Android NDK bug.
• AOT and AOT+LLVM on x86 are known to be unstable.
• AOT+LLVM on arm64-v8a is known to be unstable.

There are several changes which may alter the development workflow in this release.

• Change minSdkVersion Default Value.
• Cross-VM Exception Propagation.
• JNIEnv.NewObjectArray() Array Type.
• ApplicationInfo.nativeLibraryDir Use.
• GREF Logging Changes.

Note: The default minSdkVersion may change in the future with minimal or no notice. API-11 was chosen because that was the minimum required to make Activity.ActionBar not return null (it's value depends upon minSdkVersion). If we find other Android functionality which is dependent upon minSdkVersion, we may bump minSdkVersion higher so that default projects may more easily make use of it.

Previously, native libraries were assumed to be in ApplicationInfo.dataDir + "/lib"... because that was the only thing that would work on API-4.

Unfortunately, that logic no longer works for 64-bit platforms, as native libraries for 64-bit platforms are in a different (variable) location. 64-bit runtime support instead requires searching for native libraries within the directory stored in ApplicationInfo.nativeLibraryDir.

To support 64-bit runtimes, when AndroidManifest.xml contains a //uses-sdk element with an android:minSdkVersion attribute value that is 10 or later, then native libraries will instead be searched within ApplicationInfo.nativeLibraryDir. If the android:minSdkVersion attribute value is less than 10, then the previous behavior will be used.

As a consequence of this, it is not possible for applications to contain both an android:minSdkVersion value that is less than 10 and provide 64-bit runtime support.

adb shell run-as @PACKAGE_NAME@ cat files/.__override__/grefs.txt

adb shell setprop debug.mono.log gref=/path/to/grefs.txt

Note: To perform the above adb shell run-as command, the app must also be debuggable. Debug configuration builds are debuggable by default; Release builds are not. If a Release build needs to log GREF and provide information, it can be made debuggable by doing one of the following:

1. Edit Properties\AndroidManifest.xml and edit the <application/> element to add the attribute content:

    android:debuggable="true"
   

2. Edit Properties\AssemblyInfo.cs and add the following custom attribute:

    [assembly: Application (Debuggable=true)]
   

Note: grefs.txt can get very large, and may consume lots of disk space on the target device.

Note: grefs.txt is deleted on app startup.

There are several breaking changes in this release, many of which have been hinted at previously via [Obsolete] messages, some of which are semantic changes which won't break compilation but may affect runtime behavior.

• Removal Of Property Setters for final Fields.
• Removal of API Levels.
• Removal of Obsolete Assemblies.
• Android Callable Wrapper Naming.

The Mono.Android.GoogleMaps.dll, Mono.Android.Support.v4.dll, and Mono.Android.Support.v13.dll assemblies have been removed. (All types in these assemblies were obsoleted in Xamarin.Android 4.14)

Please migrate to the corresponding Xamarin Components:

• Mono.Android.GoogleMaps: Please use the Google Play Services component.
• Mono.Android.Support.v4.dll: Please use the Android Support Library v4 component.
• Mono.Android.Support.v13.dll: Please use the Android Support Library v13 component.

adb shell am start -n My.Package.Name/my.ActivityType

Instead, I would suggest that you use RegisterAttribute, BroadcastReceiverAttribute.Name, ContentProviderAttribute.Name, ActivityAttribute.Name, ApplicationAttribute.Name, or ServiceAttribute.Name.

For example, if you previously had:

namespace My {
    [Activity]
    public partial class ActivityType : Activity {
        /* ... */
    }
}

Then to maintain compatibility with your scripts/external code, set the ActivityAttribute.Name property:

namespace My {
    [Activity(Name="my.ActivityType")]
    public partial class ActivityType : Activity {
        /* ... */
    }
}

For a more complete example, this change was responsible for causing the ApiDemo sample to crash on startup because ApiDemo used //activity/@android:name instead of the [Activity] custom attribute in several locations, and in Xamarin.Android 5.0 this resulted in an "inconsistency" between AndroidManifest.xml and the actual Java files. The fix for ApiDemo involves using ActivityAttribute.Name and removing the XML fragments from AndroidManifest.xml, as deemed appropriate.

To assist with the transition, AndroidManifest.xml will be checked for references to previously generated type names and all such references will be automatically fixed up to use the new convention. This only affects the contents of AndroidManifest.xml.

• Numerious MSBuild target cleanup and improvements
• Fix System.Linq.Expressions linking
• Add Android.App.ActivityAttribute.Immersive property value, which sets the //activity/@android:immersive attribute value.
• Generate XA0101 warning if the @(Content) Build action is used, as the @(Content) Build action can't be supported.
• Improve display of aapt errors within the IDE errors panel.
• 2461 The AppDomain.UnhandledException event doesn't work.
• 7634: Managed > Java > Managed Exception Propoagation is broken.
• 8470: Support Deploying to Android 4.2+ with non-admin current user.
• 10268: Linker issue with horizontallistview project in release mode.
• 11270: Linker failure.
• 12935: sensorPortrait should be sensorPortait on API < 16
• 13154: Display SHA1 fingerprint of the keystore that was used to sign an .apk.
• 15205#c1, 16826, 21147: Support same namespace+type in separate assemblies for Java.Lang.Object subclasses.
• 16409: Fix InvalidOperationException from AndroidEnvironment._Proxy.Credentials property.
• 16805: Allow <fragment class="..."> to contain assembly-qualified type names.
• 16826: ACWs: Create unique package names instead of lowercasing the namespace.
• 17257: NoSuchMethodError when using TreeViewObserver.GlobalLayout on targets before API level 16.
• 17313: Properly generate XPath method reference comments within generated bindings code.
• 19391: [Preserve(AllMembers=true)] not working when [DataContract] is after it.
• 21034: mandroid generates XA0000 for Out of memory.
• 21159: Incorrect super() constructor invocation generated in Android Callable Wrappers for Android.Graphics.Canvas subclasses.
• 21361: Attribute name has already been defined, when having attributes defined in a Android Class Library and using Android Binding component
• 21578: System.Net.Sockets.Socket.SetSocketOption removed by the linker.
• 22155: Fix jar2xml to properly emit generic type constraints.
• 22218: [generator] Parameter marshaling is not exception-safe.
• 22670: Build warnings after referencing Microsoft.Net.Http NuGet package in Xamarin.Android app project.
• 22912: DateTime.Now gives NullReferenceException in other AppDomains.
• 22955: Basic DateTime calcutions are now throwing exceptions.
• 22959: javac generates no suitable constructor found for RuntimeException(String,Throwable,boolean,boolean) message when inheriting from Java.Lang.RuntimeException.
• 22962: @deprecated annotations aren't mapped to C#'s [Obsolete] attribute.
• 22968: Crash when lazy loading assemblies.
• 23077: Wrap DriveInfo to StatFs.
• 23405: DateTime.Now returns time off by 1 hour
• 23564: Setting WindowSoftInputMode to SoftInput.AdjustNothing on Activity generates an out of range exception on compilation.
• 23617: Can't build in Release mode: Error executing task GenerateJavaStubs: Could not load assembly 'Xamarin.Android.Support.v4'
• 23950: TimeZone.CurrentTimeZone.GetDaylightChanges() contains the wrong End value for AEDT.
• 23990: Error when building a project with a TargetFramework < v2.3 should be improved and standardized.
• 24086: Fix TimeZoneInfo transitions for Asia/Amman.
• 24193: generator generates a .JavaCast<byte[]>() expression, which doesn't compile.
• 24206: "Access to the path ...\obj\Debug\__library_projects__\...\library_project_imports\assets\... is denied" when asset files in class library are marked as read-only
• 24405: org.apache.http.impl.auth.BasicScheme not bound.
• 24497: Certain APIs break linking due to inter-API-level differences.
• 24612: Referencing a library project's resources with upper case letters in filenames does not work.
• 24809: Add support for manifest merging when using Android libraries.
• 24820: Make temp files for Xamarin.Android that are automatically cleaned.
• 24947: Current TimeZone is not updated after the system timezone is changed by a java call.
• 25022: License fails if no network connection.
• 25157: SierpinskiTetrahedron sample doesn't appear and has loop of output on some devices.
• 25443#c8: Don't call JNIEnv::GetObjectRefType() with a NULL JNI handle, to avoid an Android bug.
• 25508: android.net.wifi.WifiConfiguration.status not bound.
• 25990: JIT Crash on Lollipop with SIGSEGV error because Android Callable Wrapper static constructor executed from unregistered thread.
• 26074: InvalidCastException from JNIEnv.GetArray<Java.Lang.Object>(byteArrayArray).
• 26617: Android.Graphics.Color.Green isn't really green.
• 26864: Preserve type reference targets within custom attributes for linking.
• 27408: Crash in SynchronizationContext.Post().
• 28781: PCL MDB files are not generated and PCL breakpoints don't work.

Xamarin.Android uses Mono 4.0 commit fe127993.

• 1849: TimeZoneInfo.ConvertTime() gives wrong result when converting from UTC to UTC.
• 1852: XmlSerialization ignores ShouldSerialize* and *Specified
• 6512: Don't parse JSON when using GET
• 7716: Cannot validate signed XML generated on Windows in Linux, and vice versa.
• 14277: Stepping in static constructor exits.
• 17944: mini-amd64.c:492: amd64_patch: Assertion 0' failed.` with jagged array ctors which create an array of arrays.
• 18422: HttpClient doesn't support 'name[]' header field name format
• 18800: IndexOutOfRangeException when MultipartFormDataContent filename value contains whitespace.
• 19012: XmlArrayItemAttribute.IsNullable default does not match MS.NET default.
• 19039: Runtime crashes when evaluating FieldInfo.MetadataToken in Dynamic Assembly.
• 19334: Failure at System.Net.Sockets.NetworkStream.BeginWrite().
• 19823: InvalidOperationException in ServicePoint.RemoveConnectionGroup().
• 19881: ProductInfoHeaderValue fails to parse User-Agent string without version
• 20403: InvalidOperationException when XML-serializing System.Drawing.Color
• 20764: WebMessageFormatter crashes with void return type OperationContract
• 21072: DataContractSerializer does not serialize enum flags the same as .net 4.
• 21135: Deadlock in WebConnectionStream.
• 21172: text field type nvarchar(max) is truncated to 4000 chars.
• 21571: Uri.GetComponents() should allow UriComponents.SerializationInfoString on relative Uri
• 21653: App crashed attempting to debug: Assertion, mono_error_ok (&error) not met.
• 22212: Error parsing DateTime string in New Zealand Culture.
• 22383: HttpClient's RequestMessage.RequestUri.AbsoluteUri don't automatically point to right ones on 302
• 22417: DateTime.Parse() does not correctly recognize the date with correct format
• 22557: HttpValueCollection does not properly url encode values in ToString() method
• 22558: DateTimeOffset.Parse() can't handle the dateTime string without time part.
• 22591: Default BigInteger causes exceptions and incorrect answers
• 22685: Assertion at mini.c:4656, condition cfg->code_size - cfg->epilog_begin < 0xffff not met
• 22704: ClientWebSocket cannot handle reading subsets of the payload
• 22764: HTTP POST ContentType is null instead of one sent by client in case of MultipartFormDataContent
• 22775: Flawed implementation of BlockingCollection(T).AddToAny - Only blocks on first collection
• 22851: DateTimeOffset.Parse() doesn't handle RFC1123 formatted timestamps correctly
• 22857: DirectoryInfo.EnumerateFileSystemInfos() with SearchOption.AllDirectories does not return all subdirectories
• 23021: Calls from generic shared methods not always patched.
• 23077: Wrap DriveInfo to StatFs.
• 23206: Microsoft allows threadpool threads to be renamed multiple times
• 23242: Null reference exception occurs after the call to int.ToString() from multiple threads
• 23318: XComment throws an exception with some inputs
• 23376: TimeSpan returns incorrect result.
• 23392: Assertion at mini-codegen.c:2307, condition sp < 8 not met
• 23423: SIGABRT and crash in System.Diagnostics.Process
• 23438: ECMA-335 Type layout attributes and atomic operations: a generic type shall not have explicit layout
• 23594: A task will not complete if an exception is thrown in an attached child task with a task continuation that specifies TaskContinuationOptions.NotOnFaulted
• 23700: App using SocketAsyncEventArgs sometimes crash with ObjectDisposedException, stacktrace starts in DispatcherCB
• 23769: Getting NotSupportedExceptions when performing reflection on generic types defined in dynamic assemblies
• 24109: SoundPlayer corrupts memory, leading to crashes
• 24221: Sorting of large structs with wrong result.
• 24340: Some WebSocket unit tests (System) fails silently
• 22346: Fixed DeflateStream native error when handling empty input.
• 22501: XmlSchema.Read() raises InvalidElementError for certain inputs which work fine in MS.NET
• 22775: BlockingCollection<T>.AddToAny() only blocks on first collection.
• 22968: Crash when lazy loading assemblies.
• 23058: DataContractJsonSerializer - Deserialize type incorrect on iOS.
• 23242: NullReferenceException occurs after the call to int.ToString() from multiple threads
• 23401: Sgen's marksweep-conc fails under load test.
• 23423: SIGABRT and crash in System.Diagnostics.Process
• 23594: A task will not complete if an exception is thrown in an attached child task with a task continuation that specifies TaskContinuationOptions.NotOnFaulted
• 23769: Getting NotSupportedExceptions when performing reflection on generic types defined in dynamic assemblies
• 23771: UTF8 Decoder's Convert() does not keep internal state between calls when 'flush' parameter is false
• 23808: HMACSHA256 default ctor creates 64-bit key, expected 64-byte.
• 23954: Missing checks for overlapping reference and non-reference fields.
• 23966: HttpClient.GetStreamAsync() behaves differently from .NET.
• 24084: sgen assert in sgen_obj_get_descriptor() when frequently allocating with FormatterServices.GetUninitializedObject()
• 24213: ConcurrentBag.TryTake() returns the same instance twice...
• 24419: Synchronized static methods of generic classes lock on the open type instead of the closed one
• 24431: CultureInfo constructor error message decimal and hex lcid should be different.
• 24577: Fatal Unhandled Exсeption: System.FormatException
• 24611: System.Net.WebException when using the FtpWebRequest with non-ASCII characters in the URL.
• 24704: System.Net.Http.HttpClient.PostAsync() ignores timeout if webproxy isn't accessible.
• 24757: LogicalCallContext not flowing with async calls.
• 24775: List<T>.ForEach() does not throw InvalidOperationException when collection was modified.
• 24891: Parallel.ForEach() overload always sets -1 as current element index.
• 25059: StructLayout.Pack >= 16 throws TypeLoadException at runtime
• 25087: System.Uri constructor throws an exception when parsing an HTTP URI with a username or password that contains certain escaped characters
• 25132: SafeHandle always called with Dispose(true).
• 25158: TypeDescriptor.GetConverter(typeof(DateTimeOffset)) do not return DateTimeOffsetConverter.
• 25224: stack overflow after printfn something.
• 25498: System.IO.SynchronizedStream does not call Close on wrapped Stream.
• 25664: FieldInfo.GetValue() causes segmentation fault when field is of pointer type
• 25679: Memory leak and buffer overflow in get_gsharedvt_type().
• 25720: Runtime crashing when evaluating System.Diagnostics.Process.HasExited property
• 25808: DataContractJsonSerializer cannot deserialize array to IEnumerable<T>.
• 25850: SafeHandle.Close() is not idempotent.
• 25895: Wrong exception is thrown when calling System.Globalization.CharUnicodeInfo.GetNumericValue(string s, int index) with invalid index
• 25928: Barrier constructed with 0 participants will hang on AddParticipant.
• 26008: Wrong DST when TimeZoneInfo has floating date rules.
• 26033: Set next statement(CMD_THREAD_SET_IP) + stepping doesn't work as expected
• 26109: System.Net.Http.Headers.RangeHeaderValue fails to parse with large byte range
• 26127: SafeHandle types + Delegates + Marshal.GetDelegateForFunctionPointer() == Possible crash
• 26312: webClient.UploadFile(ftpPath, filePath) adds some header information to the uploaded file..
• 26412: ConstructorInfo.ContainsGenericParameters behaves differently to MS.NET
• 27010: Difference in Assembly.GetExportedTypes() with .NET
• 27036: Adding the user-agent header to HttpClient object throws a System.FormatException: Invalid format.
• 27086: Writing in asynchronous FileStream adds 0 bytes at the beginning of the file.
• 27352: HttpRequestMessage: adding Accept header with multiple values fails
• 27386: HttpClient doesn't honor BaseAddress with the Get*Async() methods.
• 27697: Debugger crash: error: * Assertion at ../../../../../mono/mono/mini/debugger-agent.c:2475, condition `tls' not met
• 28331: Custom Attributes incompatability
• 28383: Marshal.AllocCoTaskMem(0) incorrectly returns IntPtr.Zero.

• API Level 10: Mono.Android.dll, OpenTK.dll, OpenTK-1.0.dll
• API Level 15: Mono.Android.dll
• API Level 16: Mono.Android.dll
• API Level 17: Mono.Android.dll
• API Level 18: Mono.Android.dll
• API Level 19: Mono.Android.dll
• API Level 20: Mono.Android.dll
• API Level 21: Mono.Android.dll