Error MSB4018: The "DetectSdkLocations" task failed unexpectedly.

[Leo506]

Apple platform

iOS

Framework version

net10.0-*

Affected platform version

.NET: 10.0.300 iOS: 26.5.10280

Description

After releasing the last version of iOS workloads (with support Xcode 26.5) my app is failed to build on Microsoft Azure Agent with error:
##[error]/Users/runner/hostedtoolcache/dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.5/26.5.10280/tools/msbuild/Xamarin.Shared.targets(2091,3): Error MSB4018: The "DetectSdkLocations" task failed unexpectedly.

The same error on my personal Mac

Steps to Reproduce

1. Update .Net to 10.0.300 and install the last iOS workloads
2. Try to build any .net10-ios project
3. Error

Did you find any workaround?

No response

Build logs

System.TypeInitializationException: The type initializer for 'Xamarin.MacDev.AppleSdkSettings' threw an exception.
       ---> System.ArgumentNullException: Value cannot be null. (Parameter 'path')
         at System.ArgumentNullException.Throw(String paramName)
         at System.ArgumentNullException.ThrowIfNull(Object argument, String paramName)
         at System.ArgumentException.ThrowNullOrEmptyException(String argument, String paramName)
         at System.IO.Directory.CreateDirectory(String path)
         at Xamarin.MacDev.AppleSdkSettings..cctor() in /Users/builder/azdo/_work/1/s/macios/external/Xamarin.MacDev/Xamarin.MacDev/AppleSdkSettings.cs:line 145
         --- End of inner exception stack trace ---
         at Xamarin.MacDev.AppleSdkSettings.Init() in /Users/builder/azdo/_work/1/s/macios/external/Xamarin.MacDev/Xamarin.MacDev/AppleSdkSettings.cs:line 156
         at Xamarin.MacDev.Tasks.DetectSdkLocations.ExecuteImpl() in /Users/builder/azdo/_work/1/s/macios/msbuild/Xamarin.MacDev.Tasks/Tasks/DetectSdkLocation.cs:line 148
         at Xamarin.MacDev.Tasks.DetectSdkLocations.Execute() in /Users/builder/azdo/_work/1/s/macios/msbuild/Xamarin.MacDev.Tasks/Tasks/DetectSdkLocation.cs:line 130
         at Microsoft.Build.BackEnd.TaskExecutionHost.Execute()
         at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(TaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket buc
      ket, TaskExecutionMode howToExecuteTask)

[JonnySKK]

This issue is also impacting our Azure DevOps pipeline builds for a .NET MAUI app, i.e. we are seeing the same failure during the iOS build step on hosted macOS agents. It was working fine yesterday.

[tranb3r]

Same issue for me on windows with pair2mac.

C:\Program Files\dotnet\packs\Microsoft.iOS.Sdk.net10.0_26.5\26.5.10280\tools\msbuild\Xamarin.Shared.targets(2091,3): warning : [xma][err]: An exception occurred in the task 'DetectSdkLocations'
C:\Program Files\dotnet\packs\Microsoft.iOS.Sdk.net10.0_26.5\26.5.10280\tools\msbuild\Xamarin.Shared.targets(2091,3): warning : exception: An error occurred on client Build26510280 while executing a reply for topic xvs/build/26.5.10280/execute-task/mytestproject/b16c961002fDetectSdkLocations
C:\Program Files\dotnet\packs\Microsoft.iOS.Sdk.net10.0_26.5\26.5.10280\tools\msbuild\Xamarin.Shared.targets(2091,3): warning : The type initializer for 'Xamarin.MacDev.AppleSdkSettings' threw an exception.

[filipnavara]

We started hitting this today (new workloads?) on our self-hosted GitHub Actions runners.

(Perhaps related to dotnet/macios-devtools#179 ?)

[Leo506]

@filipnavara yes, you are right. This issues causes build fail.
As workaround I tried to create file at ~/Library/Preferences/maui/Settings.plist

[tranb3r]

As workaround I tried to create file at ~/Library/Preferences/maui/Settings.plist

This workaround works for me. Thanks!

[dalexsoto]

@filipnavara yes, you are right. This issues causes build fail. As workaround I tried to create file at ~/Library/Preferences/maui/Settings.plist

Thank you for the workaround!

We have started the release process for the fix to this issue, sorry about that!

[mitchelsellers]

As workaround I tried to create file at ~/Library/Preferences/maui/Settings.plist

Did you have any specific content in that file? We tried that and still getting failures

[filipnavara]

Did you have any specific content in that file? We tried that and still getting failures

I used defaults write ~/Library/Preferences/maui/Settings.plist TEST_VAR 1.

[mitchelsellers]

Just a note for others. I added this step to my GitHub actions, using the latest xcode version.

    - name: Temporary Silly fix
      run: |
        mkdir -p ~/Library/Preferences/maui
        defaults write ~/Library/Preferences/maui/Settings.plist TEST_VAR -int 1

But now I get this one, so one step closer but still totally broken on our side, pinning back versions etc hasn't worked either.

  <dict>
  	<key>com.apple.actool.compilation-results</key>
  	<dict>
  		<key>output-files</key>
  		<array>
  			<string>/Users/runner/work/climb-tms-application/climb-tms-application/src/MyApp/obj/Release/net10.0-ios/ios-arm64/actool/bundle/appicon60x60@2x.png</string>
  			<string>/Users/runner/work/climb-tms-application/climb-tms-application/src/MyApp/obj/Release/net10.0-ios/ios-arm64/actool/bundle/appicon76x76@2x~ipad.png</string>
  			<string>/Users/runner/work/climb-tms-application/climb-tms-application/src/MyApp/obj/Release/net10.0-ios/ios-arm64/actool/partial-info.plist</string>
  		</array>
  	</dict>
  	<key>com.apple.actool.errors</key>
  	<array>
  		<dict>
  			<key>description</key>
  			<string>No simulator runtime version from ["23B86", "23C54", "23E254a"] available to use with iphonesimulator SDK version 23F5054d</string>
  		</dict>
  	</array>
  </dict>
  </plist>

We are building directly to the ion-arm64 runtime

[rolfbjarne]

But now I get this one, so one step closer but still totally broken on our side, pinning back versions etc hasn't worked either.

This is a different problem, so please file a different problem to avoid confusion there.

That said, it's likely due to missing the latest iOS simulator (which is needed even when building for device). You can download it manually in Xcode, or run xcodebuild -downloadPlatform iOS from the command line to install it.