Develop Reference

Xamarin.Android APK crashes following migration to Visual Studio Team Services (VSTS) - android

We've got a mobile application (Xamarin.Forms for iOS and Android) that we've been in the progress of migrating from our on-premise Team Foundation Server (TFS) to Visual Studio Team Services (VSTS). For the last couple of months now we've hosted our code in VSTS but have performed the builds and releases to the respective stores from our on-premise TFS. Late last week I migrated both the build and release definitions to VSTS as well, so that now we have the entire process in VSTS.
Or so I thought... For, while the iOS build and release works fine, and Android builds and releases as well, the Android application now crashes when you attempt to run it. No major (read: no) changes have taken place in the code and neither HockeyApp nor our App's own error log are able to record the reason for the crash - nor does the Google Developer Console provide us with any insight for that matter. After a couple of tries I was able to get the following exception out of a Logcat:
I/MonoDroid(21970): UNHANDLED EXCEPTION:
I/MonoDroid(21970): System.ArgumentException: element is not of type Xamarin.Forms.View
I/MonoDroid(21970): Parameter name: element
I/MonoDroid(21970): at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].Xamarin.Forms.Platform.Android.IVisualElementRenderer.SetElement (Xamarin.Forms.VisualElement element) [0x0001c] in <fa196d4afd1b4356b38d6cf3bb1e4df8>:0
I/MonoDroid(21970): at Xamarin.Forms.Platform.Android.Platform.CreateRenderer (Xamarin.Forms.VisualElement element, Android.Support.V4.App.FragmentManager fragmentManager, Android.Content.Context context) [0x00031] in <fa196d4afd1b4356b38d6cf3bb1e4df8>:0
I/MonoDroid(21970): at Xamarin.Forms.Platform.Android.AppCompat.FragmentContainer.OnCreateView (Android.Views.LayoutInflater inflater, Android.Views.ViewGroup container, Android.OS.Bundle savedInstanceState) [0x0001b] in <fa196d4afd1b4356b38d6cf3bb1e4df8>:0
I/MonoDroid(21970): at Android.Support.V4.App.Fragment.n_OnCreateView_Landroid_view_LayoutInflater_Landroid_view_ViewGroup_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_inflater, System.IntPtr native_container, System.IntPtr native_savedInstanceState) [0x00020] in <20045e457c414d37bc46e447a5bb3bb5>:0
I/MonoDroid(21970): at (wrapper dynamic-method) System.Object.b09cff61-6f2e-471d-b43a-8d2949513eb7(intptr,intptr,intptr,intptr,intptr)
Now there's only one place in our code where we use fragments, which is in a custom renderer we use to extend the default implementation of the BottomBarPage we use instead of Xamarin's default TabbedPage. I therefore attempted a build with this feature turned off (using the default TabbedPage instead of a BottomBarPage and removing the ExportRenderer-attribute), but this did not solve the problem. Of course I also had a look online to see if I could match the error message with any problem anyone else might have experienced. Results seemed rather meager and not particularly applicable to my case: install the latest version of Xamarin.Forms (which we cannot do at the moment - besides things were working on our private build server) or do a clean and rebuild (I actually tried turning on the Clean-option in our Xamarin.Android-task, but to no effect).
I therefore proceeded to compare the last build log from TFS with a recent one from VSTS to see if I could find any major difference. This turned out to be rather tricky as the output between the two build definitions differs markedly. Superficially, they both look the same, though, performing the same tasks. I did notice, however, that our own Mac build server used newer versions of both MS Build and Android Build Tools than does the VSTS Hosted Mac (15.6.0.0 versus 15.4.0.0 and 27.0.1 versus 23.0.0 respectively), so I decided to change the build environment, as there seems to be no way to influence these parts of the build-environment and the highest installed version of the Android Build Tools will be used when none is explicitly specified anyway (according to https://learn.microsoft.com/en-us/xamarin/android/deploy-test/building-apps/build-process). Running on VS2017 Hosted now at least gives me Android Build Tools version 27.0.3. The JDK-version is the same on all environments, by the way.
With the switch in build-environment also not resolving the issue I next tried the following:
Turned off AOT-compilation - though a comparison of the log showed that what differed mostly were IDs and compression levels/final file sizes.
Verified that I deselected to use the shared runtime (as suggested here) and that both "armeabi" and "armeabi-v7a" architectures are selected for compilation (as proposed here).
Switched from using the Xamarin.Android build-task to using the shell-script which I had built for our on-premise TFS, as the latter's agent had lacked the Xamarin.Android-capability and the script was meant as a work-around.
Compared the list of Android resources reported by the log as included in the build, which was equal.
Compared the list of intermediate assemblies reported by both build logs as being packaged and found them to be more or less equal (with the new VSTS-build adding unfamiliar Mono.Data.Tds.dll- and System.Runtime.InteropServices.RuntimeInformation.dll-assemblies).
Performed a per-project comparison of copied files reported by the build logs - something I found of little informative value, since I considered additional assemblies & files reported by VSTS harmless, but am otherwise unable to evaluate the impact of files reported by TFS but not reported by VSTS (in other words, I'm unsure of the informative value of comparing the lists of copied files).
Verified the list of files reported by both logs as having been signed and zip-aligned (the configuration between TFS and VSTS is completely the same, therefore this task has received little attention in my investigation otherwise).
Made a build on VSTS from the same branch and commit as the last-known working one made on TFS and compared these using Android Studio's APK analysis/package comparison tool.
Only the latter - the package comparison - I've found to be informative, yet of what I do not know. That is to say, one would expect packages containing exactly the same code and resource files to have little difference among them except for maybe the version numbers in the Android-manifest. And, indeed, this is what I'm seeing for the assets and resources. However, significantly (at least in my opinion), the META-INF, lib, classes.dex, assemblies and typemap-files all differ in size. It is unclear to me what this means, though...
Now about 1.5 days in, the only promising result so far is another post here on Stack Overflow that seems to describe the same symptoms as we're experiencing, yet reports a different exception message in their logcat. No resolution has been posted, however.
Edit 1
One thing I've noticed just now when comparing the Android-manifest between builds made on TFS versus those made on VSTS is that the following metadata is lacking from the application-node when building on VSTS (yet is present in local [debug-]builds):
<meta-data
android:name="android.support.VERSION"
android:value="26.1.0" />
I'm unsure what package adds this node and what it does, however, but feel it might be significant and will be investigating this further.
Edit 2
After a long day of frustration trying all kinds of different combinations of libraries (some of which don't seem to want to install on the .NetStandard projects VS2017 creates for mobile Apps by default instead of the old PCL), I managed to narrow down where the above entry in the Android-manifest comes from: apparently this is something that the version 26.1.0 Xamarin Android support libraries add. It turns out that one of the Xamarin Android support libraries referenced in the CS-project-file of one of the three Android-projects our App uses was still pointing towards an old 26.1.0.1 version, whereas all other references had been updated to 27.0.2. Changing this entry manually ensured that entry in the Android-manifest went away. This, however, did, unfortunately, not solve our build issues with the Android-version of our App...
Edit 3
Building on a hosted VS2017 environment now results in the below exception messages:
C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Common.targets(2374):C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Common.targets(2374,3): Error : error XA5101: Missing Android NDK toolchains directory '\toolchains'. Please install the Android NDK. at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainDirectories(String toolchainsPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainPath(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkTool(String androidNdkPath, AndroidTargetArch arch, String tool) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolPrefix(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.Aot.<GetAotConfigs>d__73.MoveNext() at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerable.GrabChunk_Buffered(KeyValuePair`2[] destArray, Int32 requestedChunkSize, Int32& actualNumElementsGrabbed) at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerator.GrabNextChunk(Int32 requestedChunkSize) at System.Collections.Concurrent.Partitioner.DynamicPartitionEnumerator_Abstract`2.MoveNext() at System.Threading.Tasks.Parallel.<>c__DisplayClass42_0`2.<PartitionerForEachWorker>b__1() at System.Threading.Tasks.Task.InnerInvoke() at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object )
C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Common.targets(2374):C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Xamarin\Android\Xamarin.Android.Common.targets(2374,3): Error XA3001: System.AggregateException: One or more errors occurred. ---> System.AggregateException: One or more errors occurred. ---> Java.Interop.Tools.Diagnostics.XamarinAndroidException: error XA5101: Missing Android NDK toolchains directory '\toolchains'. Please install the Android NDK. at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainDirectories(String toolchainsPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainPath(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkTool(String androidNdkPath, AndroidTargetArch arch, String tool) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolPrefix(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.Aot.<GetAotConfigs>d__73.MoveNext() at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerable.GrabChunk_Buffered(KeyValuePair`2[] destArray, Int32 requestedChunkSize, Int32& actualNumElementsGrabbed) at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerator.GrabNextChunk(Int32 requestedChunkSize) at System.Collections.Concurrent.Partitioner.DynamicPartitionEnumerator_Abstract`2.MoveNext() at System.Threading.Tasks.Parallel.<>c__DisplayClass42_0`2.<PartitionerForEachWorker>b__1() at System.Threading.Tasks.Task.InnerInvoke() at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object ) --- End of inner exception stack trace --- at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions) at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken) at System.Threading.Tasks.Task.Wait() at System.Threading.Tasks.Parallel.PartitionerForEachWorker[TSource,TLocal](Partitioner`1 source, ParallelOptions parallelOptions, Action`1 simpleBody, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally) at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally) at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body) at Xamarin.Android.Tasks.Aot.RunParallelAotCompiler(List`1 nativeLibs) at Xamarin.Android.Tasks.Aot.<>c__DisplayClass71_0.<DoExecute>b__0() at System.Threading.Tasks.Task`1.InnerInvoke() at System.Threading.Tasks.Task.Execute() --- End of inner exception stack trace --- at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions) at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification) at System.Threading.Tasks.Task`1.get_Result() at Xamarin.Android.Tasks.Aot.DoExecute() at Xamarin.Android.Tasks.Aot.Execute() ---> (Inner Exception #0) System.AggregateException: One or more errors occurred. ---> Java.Interop.Tools.Diagnostics.XamarinAndroidException: error XA5101: Missing Android NDK toolchains directory '\toolchains'. Please install the Android NDK. at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainDirectories(String toolchainsPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainPath(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkTool(String androidNdkPath, AndroidTargetArch arch, String tool) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolPrefix(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.Aot.<GetAotConfigs>d__73.MoveNext() at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerable.GrabChunk_Buffered(KeyValuePair`2[] destArray, Int32 requestedChunkSize, Int32& actualNumElementsGrabbed) at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerator.GrabNextChunk(Int32 requestedChunkSize) at System.Collections.Concurrent.Partitioner.DynamicPartitionEnumerator_Abstract`2.MoveNext() at System.Threading.Tasks.Parallel.<>c__DisplayClass42_0`2.<PartitionerForEachWorker>b__1() at System.Threading.Tasks.Task.InnerInvoke() at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object ) --- End of inner exception stack trace --- at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions) at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken) at System.Threading.Tasks.Task.Wait() at System.Threading.Tasks.Parallel.PartitionerForEachWorker[TSource,TLocal](Partitioner`1 source, ParallelOptions parallelOptions, Action`1 simpleBody, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally) at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally) at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body) at Xamarin.Android.Tasks.Aot.RunParallelAotCompiler(List`1 nativeLibs) at Xamarin.Android.Tasks.Aot.<>c__DisplayClass71_0.<DoExecute>b__0() at System.Threading.Tasks.Task`1.InnerInvoke() at System.Threading.Tasks.Task.Execute() ---> (Inner Exception #0) Java.Interop.Tools.Diagnostics.XamarinAndroidException: error XA5101: Missing Android NDK toolchains directory '\toolchains'. Please install the Android NDK. at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainDirectories(String toolchainsPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolchainPath(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.NdkUtil.GetNdkTool(String androidNdkPath, AndroidTargetArch arch, String tool) at Xamarin.Android.Tasks.NdkUtil.GetNdkToolPrefix(String androidNdkPath, AndroidTargetArch arch) at Xamarin.Android.Tasks.Aot.<GetAotConfigs>d__73.MoveNext() at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerable.GrabChunk_Buffered(KeyValuePair`2[] destArray, Int32 requestedChunkSize, Int32& actualNumElementsGrabbed) at System.Collections.Concurrent.Partitioner.DynamicPartitionerForIEnumerable`1.InternalPartitionEnumerator.GrabNextChunk(Int32 requestedChunkSize) at System.Collections.Concurrent.Partitioner.DynamicPartitionEnumerator_Abstract`2.MoveNext() at System.Threading.Tasks.Parallel.<>c__DisplayClass42_0`2.<PartitionerForEachWorker>b__1() at System.Threading.Tasks.Task.InnerInvoke() at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object )<--- <---
Process 'msbuild.exe' exited with code '1'.
I'm not - as far as I'm aware - using the Android NDK, so I don't quite understand why I'm getting this exception message now. However, the VSTS hosted Mac environment doesn't seem to experience these problems (yet), so I'm switching back to building on Mac.
Edit 4
Did some searching, and apparently the above exception messages are due to problems with the automated update of Visual Studio from version 15.6 to version 15.7, which recently took place (source). Always nice to see these things being checked global roll-out.
Edit 5
So here are some further things I've tried since the last update: explicitly setting the JDK-version used by Xamarin.Android to version 8 and the JDK Architecture to x64 (as described here); and removing all custom renderers for Android, since the original exception seems to point at the VisualElementRenderer<TElement>, which is the base class for almost all (if not all) default and custom renderers. All of this to no avail, however, so that I suspect the exception thrown derives from within Xamarin.Forms itself.
Edit 6
We finally tried adding the Mac we use for our internal build flow in TFS as a private build agent to VSTS today, which was a surprisingly easy thing to do! We didn't even need to change our firewall configuration, as it seems that the agent makes connection with the server (across HTTP and HTTPS), not the other way around (we followed the steps described here). I would that all installations were this easy!
Notwithstanding the ease with which we configured our private build agent, we still experienced the same crash following builds, irrespective of whether we built with the Xamarin.Android build-task or our custom build script (which we had previously used on the very same machine from within TFS with success).
We did eventually bump into the solution by following up on a suggestion made here, however, something that seemed somewhat unrelated and not pertinent before. Yet, as I had coincidentally just updated the version of our Xamarin.Forms from version 2.5.1.444934 to version 2.5.1.527436 the day before, I decided to try running a build with this code. Which turned out to work! I've got no clue why though... But I guess that's less relevant than being able to build again!

As it turns out, updating Xamarin.Forms is the solution.
Though suggested as resolution to the same error as ours on the Xamarin forums, and something I had come across before, the age of the post and the old version of Xamarin.Forms involved made me disregard this option as less relevant to our problem. What didn't help either was that I thought we were already on the highest version of Xamarin.Forms 2.5.1, and are not quite ready to move to Xamarin.Forms 3.0 yet. Yesterday, however, I discovered there was still a revision we could upgrade within the 2.5.1-branch, which is what I did. When I then tried a build with this code, surprisingly the resulting APK turned out to run without any issue!
The reason why updating Xamarin.Forms works is unclear to us, though. We did, however, observe that this particular version of Xamarin.Forms, 2.5.1.527436, was released just about a week before I migrated our build definition from TFS to VSTS. It might therefore be that there's some correlation there.
Edit 1
Ran into some trouble with Xamarin.Forms 2.5.1.527436 today, which has eventually led me to the most likely cause for our problems creating an Android build of our App. That is, in order to resolve a crash caused by Xamarin.Forms, I tried to revert Forms to the last version I knew still worked. However, the problem with Xamarin.Forms persisted, even after the downgrade. This triggered me to inspect the project-files and compare the working version of the App to that which had been downgraded, yet should have ended up the same notwithstanding.
As it turns out some project files had references to two different versions of Xamarin.Forms: the one that I had intended to use, and the one we had been using before that. Now this mixture didn't cause any problems while running on a local development machine, since this machine would have both old and new versions of Xamarin.Forms installed and there would therefore not be any missing assemblies. However, I can imagine that this would not be the case when running a VSTS-build on a build-server. Moreover, the project files containing the incorrect assembly references were both Android projects - which explains why iOS had no trouble building...!

Related

I'm new to NativeScript and took over a project recently upgraded from NativeScript 4 to 6. Here is my environment detials:
Windows 10
Node v16.6.1
NativeScript 8.0.2
Android Studio 11 (with al
the recommended updates to date)
VS Code 1.58.2
I can create a new Native script project with "tns create" and build/run it in the simulator just fine. However, when I try to run the project the build throws the following error:
java.lang.RuntimeException: Class not found android.support.v4.view.ViewPager.OnPageChangeListener
at org.nativescript.staticbindinggenerator.Generator.getClass(Generator.java:551)
at org.nativescript.staticbindinggenerator.Generator.getInterfacesFromCache(Generator.java:534)
at org.nativescript.staticbindinggenerator.Generator.writeBinding(Generator.java:283)
at org.nativescript.staticbindinggenerator.Generator.generateBinding(Generator.java:171)
at org.nativescript.staticbindinggenerator.Generator.processRows(Generator.java:234)
at org.nativescript.staticbindinggenerator.Generator.generateBindings(Generator.java:121)
at org.nativescript.staticbindinggenerator.Generator.writeBindings(Generator.java:97)
at org.nativescript.staticbindinggenerator.Main.main(Main.java:55)
Here is the run command I'm using: "tns run android --emulator"
I have tried tons of things and searches but no luck resolving this issue.

So I had an idea and searched with a different search engine than I normally use. I did find some ideas which helped me resolved the issue.
I had previously searched in VSCode for variations on "android.support.v4.view.ViewPager.OnPageChangeListener", but only found the log file with the error. Then I learned you have to change the filter options of the find in file search otherwise the files you are looking for can be excluded from the search results. I also used Baregrep to confirm I was getting everything.
I fixed the issue by replacing all occurrences of:
android.support.v4.view.ViewPager with androidx.viewpager.widget.ViewPager
Also you may need to install widgets:npm i tns-core-modules-widgets
Since the files where I made the changes were all non-project files (many of them in the node_modules directory) there is probably something else that involves updating Node or NativeScript that may solve this as well.
If someone else figures that out, I'll be watching this thread for updates, and thanks in advance!
Fissh

I am trying to implement firebase with xamarin.android but after downloading some nugat packages I started getting different errors and the latest one is as below:
Severity Code Description Project File Line Suppression State
Error The "XamarinBuildAndroidAarProguardConfigs" task failed unexpectedly.
System.IO.InvalidDataException: Central Directory corrupt. ---> System.IO.IOException: An attempt was made to move the file pointer before the beginning of the file.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.SeekCore(Int64 offset, SeekOrigin origin)
at System.IO.FileStream.Seek(Int64 offset, SeekOrigin origin)
at System.IO.Compression.ZipArchive.ReadEndOfCentralDirectory()
--- End of inner exception stack trace ---
at System.IO.Compression.ZipArchive.ReadEndOfCentralDirectory()
at System.IO.Compression.ZipArchive.Init(Stream stream, ZipArchiveMode mode, Boolean leaveOpen)
at System.IO.Compression.ZipArchive..ctor(Stream stream, ZipArchiveMode mode, Boolean leaveOpen, Encoding entryNameEncoding)
at Xamarin.Build.Download.XamarinBuildAndroidAarProguardConfigs.Execute()
at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext() FireBaseSolution
android target framework : 25
Some of installed references :
Xamarin.Android.Support.v4
Xamarin.Android.Support.v7.AppCompat
Xamarin.GooglePlayServices.Base
Xamarin.Firebase.Messaging
Please guide me how to resolve it.
Thanks

For me the solution was in downgrading version nuget package "Xamarin.Build.Download" to version 4.4

Answering on an old question, but this may help others if they ended up in the same situation as me (not being allowed to modify the version of Xamarin.Build.Download), here's how I fixed it:
I deleted the folders for C:\Users(username)\AppData\Local\Xamarin and C:\Users(username)\AppData\Local\XamarinBuildDownloadCache and rebuilt my solution.
What I found was that evening using the NuGet cache clearing tool in Visual Studio, these directories remained untouched.
I can only surmise that this issue can also be caused by file corruption (I might have had a faulty network connection), and the DownloadCahe blocked attempting to get the "clean" files.

On MacOS I had to wipe all folders concerning Xamarin in "~/Library/Caches". Afterwards it would build fine.

Currently trying to build android-5.1.0_r5. I've checked out the sources and made no modifications. However, when compiling I get the following error.
Checking API: checkpublicapi-current
out/target/common/obj/PACKAGING/public_api.txt:20: error 5: Added public field android.Manifest.permission.BACKUP
out/target/common/obj/PACKAGING/public_api.txt:82: error 5: Added public field android.Manifest.permission.INVOKE_CARRIER_SETUP
out/target/common/obj/PACKAGING/public_api.txt:106: error 5: Added public field android.Manifest.permission.READ_PRIVILEGED_PHONE_STATE
out/target/common/obj/PACKAGING/public_api.txt:116: error 5: Added public field android.Manifest.permission.RECEIVE_EMERGENCY_BROADCAST
******************************
You have tried to change the API from what has been previously approved.
To make these errors go away, you have two choices:
1) You can add "#hide" javadoc comments to the methods, etc. listed in the
errors above.
2) You can update current.txt by executing the following command:
make update-api
To submit the revised current.txt to the main Android repository,
you will need approval.
******************************
And diffing the public api txt files does indeed show a difference.
diff frameworks/base/api/current.txt out/target/common/obj/PACKAGING/public_api.txt
19a20
> field public static final java.lang.String BACKUP = "android.permission.BACKUP";
80a82
> field public static final java.lang.String INVOKE_CARRIER_SETUP = "android.permission.INVOKE_CARRIER_SETUP";
103a106
> field public static final java.lang.String READ_PRIVILEGED_PHONE_STATE = "android.permission.READ_PRIVILEGED_PHONE_STATE";
112a116
> field public static final java.lang.String RECEIVE_EMERGENCY_BROADCAST = "android.permission.RECEIVE_EMERGENCY_BROADCAST";
However, I cant figure out where those additional Public Fields are coming from. Any ideas?

Don't do 'make update-api' if you didn't touch anything. There additional apis came form frameworks/base/res/AndroidManifest.xml badly parsed by aapt that uses buggy system/core/libcore/String8.cpp##removeAll() they use memcpy but should be memmove for overlapping strings in memory.
This is issue on latest Debian (sid) or Ubuntu (16 maybe 15) build machines.
It's a google bug in libcore/String8.cpp. Fix is here:
https://android.googlesource.com/platform/system/core/+/dd060f01f68ee0e633e9cae24c4e565cda2032bd
This man found it (Michael Scott) and maybe some other people too. Here is his investigation: https://plus.google.com/+hashcode0f/posts/URHo3hBmfHY
Living on the Edge (of Ubuntu) ... can be painful!
I've been running Ubuntu 15.04 for a while now. It's been great
having a very current kernel alongside the latest improvements from
Ubuntu and Debian. (My past post on using zRAM ramdisk is one
example).
However, having the newest greatest toys also has it's downsides. I
recently spent 4 days troubleshooting a build break in Android which
started some time after March 25th. I'm guessing I updated packages
or inadvertently changed my glibc version.
The outcome was a build error during the checkapi stage of Android
build:
Install: /out/mydroid-ara/host/linux-x86/bin/apicheck Checking API:
checkpublicapi-last Checking API: checkpublicapi-current
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:20: error
5: Added public field android.Manifest.permission.BACKUP
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:82: error
5: Added public field android.Manifest.permission.INVOKE_CARRIER_SETUP
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:106: error
5: Added public field
android.Manifest.permission.READ_PRIVILEGED_PHONE_STATE
/out/mydroid-ara/target/common/obj/PACKAGING/public_api.txt:116: error
5: Added public field
android.Manifest.permission.RECEIVE_EMERGENCY_BROADCAST
**************************** You have tried to change the API from what has been previously approved.
To make these errors go away, you have two choices: 1) You can add
"#hide" javadoc comments to the methods, etc. listed in the
errors above.
2) You can update current.txt by executing the following command:
make update-api
To submit the revised current.txt to the main Android repository,
you will need approval.
This occurred on both of my Ubuntu 15.04 boxes and was present when
when build AOSP android-5.0.2_r1 and android-5.1.0_r1.
For those of you who are unfamiliar with this portion of the Android
build, the Android framework exports all of the public portions of the
API and makes sure that the current build matches up with what's
located under frameworks/base/api/current.txt. It does this by
parsing frameworks/base/res/AndroidManifest.xml and any of the current
device's overlay .xml files and processes items marked with various
flags in the comments above them:#SystemApi, #hide, etc. This
parsing and processing portion of the checkapi stage is done by a
binary "aapt" (Android Asset Packagng Tool). It's source is located
under frameworks/base/tools/aapt.
I started by checking for upstream fixes to the platform/build or
platform/frameworks/base projects. After striking out, I began
debugging the android build via the use of: "make checkapi
showcommands" and then manually running the commands with "strace" to
see how each binary was involved and what output it generated.
After the first few hours of debugging, it became apparent that
out/target/common/obj/APPS/frameworks-res_intermediates/src/android/Manifest.java
file had comments which were being corrupted when aapt was generating
it. I was able to make some manual changes to the AndroidManifest.xml
file and get the build to pass (removing extra portions of the
comments).
Digging deeper via strace and then looking at various static link
sources, I found that during the AndroidManifest.xml comments
processing the #SystemApi token was being filtered out via a
String8.removeAll("#SystemApi") function call. Experimentally, I
removed this part of the processing. Lo and Behold! The build
worked. Taking a closer look at the removeAll function, I was able to
pin point a memcpy function as the part of the function which was
causing corruption.
I then researched memcpy a bit and noted that you are not supposed to
use memcpy on overlapping memory addresses, instead memmove was
preferred, because it makes a copy of the source prior to any changes
being made to the destination. After changing the use of memcpy to
memmove the build was fixed and all was well with the world!
As a good player in the open source world, I immediately thought I
should upstream this incredible feat of debugging to the master branch
of system/core. BUT, alas! The fix has been in the master branch
since November 11th 2014! And hasn't been brought into any of the
current development tags! grumble
https://android.googlesource.com/platform/system/core/+/dd060f01f68ee0e633e9cae24c4e565cda2032bd
I've since contacted the Google team about this change and let them
know of my experience in hopes that we may yet see this patch in
future release tags of Android.
Conclusion: apparently glibc is undergoeing some changes and some of
those have now filtered onto my Ubuntu boxes. Where previously the
memcpy usage was incorrect but still usable, it now causes the build
break I was seeing.
If you see this kind of error in your Android builds, and you're on a
newish version of Ubuntu or Debian distrobution, you may want to try
this simple patch and see if it helps.
Hash
Big up himself!

I do see the entries in my r8 code so you are probably safe running make update-api, and when that finishes then run your make command as normal.

While compiling native code-base, I'm getting the following error -
<NDK-HOME>/platforms/android-17/arch-arm/usr/include/jni.h:235:68: error: expected ';' at end of member declaration
<NDK-HOME>/platforms/android-17/arch-arm/usr/include/jni.h:235:70: error: '\__NDK_FPABI__' does not name a type
...
With tons of repetitions.
Platform related details are as below -
Native OS: Windows 7 (64 bit) with Cygwin64
NDK Version: r9c
A similar problem has been reported here. However, even after modifying LOCAL_CFLAGS, I couldn't find the intermediate files as suggested.
Was wondering if some of you have faced this problem already and if so, do you guys have a work-around for this?

Alright, finally got rid of these __NDK_FPABI__ errors and my native code compiled just fine. Indeed, there were subtle hints in the intermediate files (*.i and *.ii) as suggested by Andrew in the link on my previous post; these are usually related to finding appropriate headers. Once relevant changes were made, things worked like a charm.
Few things I learned while debugging this issue -
The problem was related to header files. Certain headers were being picked up from /usr/include which otherwise should have been picked up from $NDK_HOME/platform/$ANDROID_VERSION/$ARCH/usr/include. Making necessary changes in the Android makefile fixed the issue for me.
Always resist the temptation of adding hot-fixes to NDK files. This will make your life a lot easier in the long run.
One should look for the intermediate files (*.i, *.ii, *s and few others) in $PROJECT_ROOT, instead of $PROJECT_ROOT/jni (assuming native code lies there).
The latest release of NDK, namely ndk-r9d fixes some of the issues with __NDK_FPABI__ related errors.
Hope this helps!

So a few days ago I got my hands on an Arduino Mega ADK board, and the last couple of nights I have been setting up my development environment, getting to grips with the tools etc. The tools and libraries all work fine, for example I can get a program written in the Processing IDE to compile and run on an Asus Eee Pad Transformer TF101 running Android 4.03. But when I get it to try to compile and run one of the pre-written examples, it gives me a compiler error:
Android SDK Tools Revision 20
Installed at C:\NVPACK\android-sdk-windows
Project Type: Application
Project Target: Android 2.3.3
API level: 10
Library dependencies:
No Libraries
API<=15: Adding annotations.jar to the classpath.
Merging AndroidManifest files into one.
Manifest merger disabled. Using project manifest only.
No AIDL files to compile.
No RenderScript files to compile.
Generating resource IDs...
Generating BuildConfig class.
BUILD FAILED
C:\NVPACK\android-sdk-windows\tools\ant\build.xml:680: The following error occurred while executing this line:
C:\NVPACK\android-sdk-windows\tools\ant\build.xml:693: Compile failed; see the compiler error output for details.
Total time: 7 seconds
And that's all the console seems to output as well, which is rather frustrating! As far as I'm aware all of my SDK versions, tools and plugins are all up to date. I've tried this using a Linux partition I have on my hard drive and it produces the same error message, although it mentions a problem with the package com.Android.future.UsbAccessory. Given what I've seen, it seems that the problem is with the tools, either my directory structure doesn't match up to what the correct setup is, or something else is wrong :S. If anyone has had similar problems, some help would be smashing! (For the record, my setup was done using the instructions on the Arduino website, although I already had the Android SDK tools installed).
Will Scott-Jackson

It sounds like your haven't added in the support library to your project and/or you haven't downloaded it into your Android SDK.
The ADK1 demokit app targets API Level 10 (Android 2.3.3); That means you need to use the support libraries in your project and that's why the compiler is complaining about level 10 library dependencies not being available. The support libraries are a separate download in the SDK Manager, so you might not have them in your development environment.
In Android API Level 12 and higher, the USB Accessory protocol was added to the framework API, so there are two different ways to use the accessory protocol. So, you don't have to use the support libraries if you are targeting Honeycomb and higher versions, but you'll have to update the demokit app code to make this work.
Hope this helps.

So I've double checked my setup and started working on a project I had in mind, it seems to import the libraries appropriately. So far so good, but when I input:
ArduinoAdkUsb arduino;
void setup() {
arduino = new ArduinoAdkUsb(this);
//Other UI initialisation etc.
}
I get this error:
##name## ##version## by ##author##
FATAL EXCEPTION: Animation Thread
java.lang.NoClassDefFoundError: com.android.future.usb.UsbManager
at cc.arduino.ADKCommunication.<init>(Unknown Source)
at cc.arduino.ArduinoAdkUsb.<init>(Unknown Source)
at
processing.android.test.sketch_120730a.
sketch_120730a.setup(sketch_120730a.java:48)
at processing.core.PApplet.handleDraw(Unknown Source)
at processing.core.PGraphicsAndroid2D.requestDraw(Unknown Source)
at processing.core.PApplet.run(Unknown Source)
at java.lang.Thread.run(Thread.java:856)
After the app has been built and installed onto the Android tablet I am using. Any thoughts how I can over come this? From what I can tell, this has no problem finding com.android.future.usb.manager to compile and install the program, but once it tries to run it can find it.

Based on this tutorial from http://stream.tellart.com/controlling-arduino-with-android/
In the examples RGB_Arduino the name, version and author variables are set at the top of the sketch.
Try adding in this section of code at the top of your arduino sketch just underneath the library imports
// accessory descriptor. It's how Arduino identifies itself to Android
char applicationName[] = "Mega_ADK"; // the app on your phone
char accessoryName[] = "Mega_ADK"; // your Arduino board
char companyName[] = "Freeware";
// make up anything you want for these
char versionNumber[] = "1.0";
char serialNumber[] = "1";
char url[] = "http://labs.arduino.cc/adk/"; // the URL of your app online
//initialize the accessory:
AndroidAccessory usb(companyName, applicationName,
accessoryName,versionNumber,url,serialNumber);