Suddenly Can't Build - Error Performing Task ACTool

All evening been happy making some code changes and testing on my Simulator and IPad. Then go to create an App Store Build (worked 2 weeks Ago) and get the following error :

/Library/Frameworks/Mono.framework/External/xbuild/Xamarin/iOS/Xamarin.iOS.Common.targets: error : Error executing task ACTool: Child element is not expected in this operation. Line 31, position 3. Build FAILED.

Now my Debug build won't build or recognise any Simulators. Not sure whats happened - common.targets file is not one I would change! This is stopping me getting my next release ready .

Any ideas?


Best Answer


  • CarloCarlo USMember, University

    I am having a similar issue since I updated to yesterday's Stable version of Xamarin. In VS 2013 this is what I am getting:

    1> Executing task: Xamarin.iOS.Tasks.ACTool
    1> Server returned an error. The remote server returned an error: (500)
    Internal Server Error.
    1> Server error code: 500
    1> Internal Server Error
    1> Remote task execution failed.
    1>Build FAILED.

    In my Mac, I get the same error but more info:

    error : Error executing task ACTool: Could not find file

    I did report it as a bug since the project was building an running fine a few minutes before the update. Can't seem to find the "missing file" in the full backups (including binaries) I have of project that was built, executed and published.

    I just reported the issue and haven't heard from Xamarin yet. But if anybody in the forum encountered and fixed (or have a workaround) and willing to share the solution... will greatly be appreciated.


  • FulvioFulvio AUMember ✭✭

    Any update on this error? I'm getting the same thing in VS2015 with the stable release as of today.

  • AshleyJacksonAshleyJackson GBMember ✭✭

    Not sure what caused it. I undid all my changes (saved by source control again) and then deleted everything - got all source fresh and built fine. Guess something had become corrupt during checkout.


  • CarloCarlo USMember, University

    Just an FYI, I do have a content.json file in my LaunchImage.launchimage
    folder. The file contains this (empty, as far as the images is concerned):

    "images": [],
    "info": {
    "version": 1,
    "author": "xcode"

    Experimenting, I copied this file in the AppIcons.appiconset folder and it
    allowed me to compile successfully. Will have to do some testing on the app to
    see if this actually solves the issue making sure that the icons properly

    Note that although the file is empty my Info.plist does show my App Icons.
    Hope this helps you guys who are looking around for a workaround.

  • I also cannot build because of this. Any Help would be awesome.

  • Mike_KMike_K USMember ✭✭

    Bump, I have no idea what's going on but I'm having the same issues. Tried to update my app to fix an issue with dialogs in iOS 9, the change did not go smoothly and I had to revert to the version I committed prior to making changes, and then any time I tried to compile it would fail without a single error.

    I've attached the relevant portion of the output that shows ACTool failing. I have VS printing output with Diagnostic level detail. Please help! :(

  • JonWhiteJonWhite USMember ✭✭

    I'm running into a very similar issue. Has anyone found a solution to this problem?

  • JonWhiteJonWhite USMember ✭✭
    edited October 2015

    Not sure if this helps anyone but I noticed that even though I was NOT using Asset Catalogs I still had with nodes in my project file. I removed this section and i was able to get past the ACTool error.

  • ChrisPerlmanChrisPerlman USMember, University
    edited October 2015

    Thanks Jon! We had the same problem, and your suggestion of editing the .csproj file worked. we removed all of the asset nodes and were able to get past the build error.

  • HighflyerHighflyer CNMember ✭✭

    Hi all, I met the similar error on building:
    -> Error: Error initializing task ACTool: Could not load type 'Xamarin.iOS.Tasks.ACTool' from assembly 'Xamarin.iOS.Tasks, Version=, Culture=neutral, PublicKeyToken=null'. (Rial.Ios)
    Anyone help me?

  • MortenKoMortenKo NOMember

    Thanks alot Mike_K! Anyone know why this suddenly became a problem?

  • kiran.9483kiran.9483 USMember

    I din't understand what is Mike_K or JonWhite are trying to mention here..Any help please...I am suddenly facing the issue.

  • JorritVenemaJorritVenema NLMember ✭✭
    edited November 2015

    I was having this exact ACTool build error and JonWhite's comment was the right solution for me.

    So if you're not using Asset Catalogs and having this error:

    • open your .csproj file in a text editor
    • remove all ImageAsset items that reference any \Resources\Images.xcassets files
    • save the file
    • reload and build in your IDE (VS/XS)
  • SebRichardsSebRichards GBMember

    I came across this issue also.

    I found the fix was to delete the ~/Library/Caches/Xamarin/mtbs/builds directory on the build server.

  • SteveSpormannSteveSpormann DEMember ✭✭

    Deleting those two entries in the project File did the trick for me, as i'am using the launch image and appicons not as sets.

    <ImageAsset Include="Resources\Images.xcassets\AppIcons.appiconset\Contents.json"> <InProject>false</InProject> </ImageAsset> <ImageAsset Include="Resources\Images.xcassets\LaunchImage.launchimage\Contents.json"> <InProject>false</InProject> </ImageAsset>

  • CarLoOSXCarLoOSX USMember ✭✭


    Go to your xcassets in iOS project. (Double click)

    Right Click on the last element your added.
    You can know the last element you added going physically to the xcassets folder in Finder and order by creation date

    Select Remove and in the popup select Delete.

    Once you have removed you have to clean and build your project.

    Now you can add again that last element and the project should run.

  • ronitaaronitaa ILMember

    @SebRichards said:
    I came across this issue also.
    I found the fix was to delete the ~/Library/Caches/Xamarin/mtbs/builds directory on the build server.


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