iOS build fails with xcodebuild crash on macos-latest (Xcode 15.4)

[SrS2225a]

Using subosito/flutter-action@v2 with macos-latest (currently macOS 14 + Xcode 15.4), the flutter build ios --release --no-codesign command fails due to an Xcode internal crash when trying to run xcodebuild -list.

Also, it seems to be an known issue: CocoaPods/CocoaPods#4465

This appears to be triggered when Flutter attempts to read Xcode project info during build preparation.

What could be the issue?

Full Back Trace

ProcessException: Process exited abnormally with exit code -6:
Command line invocation:
    /Applications/Xcode_15.4.app/Contents/Developer/usr/bin/xcodebuild -list

User defaults from command line:
    IDEPackageSupportUseBuiltinSCM = YES


2025-05-27 15:59:38.253 xcodebuild[2660:12521] [MT] DVTAssertions: ASSERTION FAILURE in DevToolsCore/Xcode3Core/LegacyProjects/Frameworks/DevToolsCore/DevToolsCore/ProjectModel/DataModel/References/SynchronizedGroups/PBXFileSystemSynchronizedAbstractGroup.m:28
Details:  Assertion failed: IDEFileSystemSynchronizedGroupsAreEnabled()
Object:   <PBXFileSystemSynchronizedRootGroup>
Method:   +allocWithZone:
Thread:   <_NSMainThread: 0x600003460200>{number = 1, name = main}
Hints: 

Backtrace:
  0   -[DVTAssertionHandler handleFailureInMethod:object:fileName:lineNumber:assertionSignature:messageFormat:arguments:] (in DVTFoundation)
  1   _DVTAssertionHandler (in DVTFoundation)
  2   _DVTAssertionFailureHandler (in DVTFoundation)
  3   _DVTAssertionWarningHandler (in DVTFoundation)
  4   -[PBXFileSystemSynchronizedAbstractGroup initWithName:path:sourceTree:] (in DevToolsCore)
  5   -[PBXPListUnarchiver _unarchiveObjectWithGlobalIDHexString:] (in DevToolsCore)
  6   -[PBXPListUnarchiver _decodeMutableObjectArrayFromPListArray:] (in DevToolsCore)
  7   -[PBXPListUnarchiver decodeMutableObjectArrayForKey:] (in DevToolsCore)
  8   -[PBXUnarchivingBinding readValueForObject:fromPListUnarchiver:] (in DevToolsCore)
  9   -[PBXObject _unarchiveValuesForArchiveMask:fromPListUnarchiver:] (in DevToolsCore)
 10   -[PBXObject readFromPListUnarchiver:] (in DevToolsCore)
 [11](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:12)   -[PBXReference readFromPListUnarchiver:] (in DevToolsCore)
 [12](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:13)   -[PBXPListUnarchiver _unarchiveObjectWithGlobalIDHexString:] (in DevToolsCore)
 [13](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:14)   -[PBXPListUnarchiver decodeObjectForKey:] (in DevToolsCore)
 [14](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:15)   -[PBXUnarchivingBinding readValueForObject:fromPListUnarchiver:] (in DevToolsCore)
 [15](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:16)   -[PBXObject _unarchiveValuesForArchiveMask:fromPListUnarchiver:] (in DevToolsCore)
 [16](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:17)   -[PBXObject readFromPListUnarchiver:] (in DevToolsCore)
 [17](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:18)   -[PBXContainer readFromPListUnarchiver:] (in DevToolsCore)
 [18](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:19)   -[PBXProject readFromPListUnarchiver:] (in DevToolsCore)
 19   -[PBXPListUnarchiver _unarchiveObjectWithGlobalIDHexString:] (in DevToolsCore)
 20   -[PBXPListUnarchiver decodeRootObject] (in DevToolsCore)
 21   +[PBXProject projectWithFile:errorHandler:readOnly:] (in DevToolsCore)
 22   -[Xcode3Project initWithFilePath:extension:workspace:options:error:] (in DevToolsCore)
 23   __82+[IDEContainer _retainedContainerAtFilePath:fileDataType:workspace:options:error:]_block_invoke_2 (in IDEFoundation)
 24   _dispatch_client_callout (in libdispatch.dylib)
 25   _dispatch_lane_barrier_sync_invoke_and_complete (in libdispatch.dylib)
 26   DVTDispatchBarrierSync (in DVTFoundation)
 27   -[DVTDispatchLock performLockedBlock:] (in DVTFoundation)
 28   __82+[IDEContainer _retainedContainerAtFilePath:fileDataType:workspace:options:error:]_block_invoke (in IDEFoundation)
 29   __58-[DVTModelObjectGraph performBlockCoalescingModelChanges:]_block_invoke (in DVTFoundation)
 30   -[DVTModelGraphTransactionScope performTransaction:] (in DVTFoundation)
 31   -[DVTModelObjectGraph performBlockCoalescingModelChanges:] (in DVTFoundation)
 32   +[IDEContainer _retainedContainerAtFilePath:fileDataType:workspace:options:error:] (in IDEFoundation)
 33   -[IDEWorkspace _configureWrappedWorkspaceWithError:] (in IDEFoundation)
 34   __82+[IDEContainer _retainedContainerAtFilePath:fileDataType:workspace:options:error:]_block_invoke (in IDEFoundation)
 35   +[IDEContainer _retainedContainerAtFilePath:fileDataType:workspace:options:error:] (in IDEFoundation)
 36   +[IDEContainer retainedWrappedWorkspaceForContainerAtFilePath:fileDataType:error:] (in IDEFoundation)
 37   -[Xcode3CommandLineBuildTool _resolveInputOptionsWithTimingSection:] (in Xcode3Core)
 38   -[Xcode3CommandLineBuildTool run] (in Xcode3Core)
 39   XcodeBuildMain (in libxcodebuildLoader.dylib)
 40   -[XcodebuildPreIDEHandler loadXcode3ProjectSupportAndRunXcode3CommandLineBuildToolWithArguments:] (in xcodebuild)
 41   -[XcodebuildPreIDEHandler runWithArguments:] (in xcodebuild)
 42   main (in xcodebuild)
 43   start (in dyld)
  Command: /usr/bin/arch -arm64e xcrun xcodebuild -list
#0      RunResult.throwException (package:flutter_tools/src/base/process.dart:118:5)
#1      _DefaultProcessUtils.run (package:flutter_tools/src/base/process.dart:344:[19](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:20))
<asynchronous suspension>
#2      XcodeProjectInterpreter.getInfo (package:flutter_tools/src/ios/xcodeproj.dart:352:30)
<asynchronous suspension>
#3      XcodeBasedProject.projectInfo (package:flutter_tools/src/xcode_project.dart:195:29)
<asynchronous suspension>
#4      XcodeBasedProject.buildSettingsForBuildInfo (package:flutter_tools/src/xcode_project.dart:[21](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:22)5:36)
<asynchronous suspension>
#5      IosProject._parseProductName (package:flutter_tools/src/xcode_project.dart:564:55)
<asynchronous suspension>
#6      IosProject.productName (package:flutter_tools/src/xcode_project.dart:552:29)
<asynchronous suspension>
#7      BuildableIOSApp.fromProject (package:flutter_tools/src/ios/application_package.dart:117:33)
<asynchronous suspension>
#8      FlutterApplicationPackageFactory.getPackageForPlatform (package:flutter_tools/src/flutter_application_package.dart:80:15)
<asynchronous suspension>
#9      _BuildIOSSubCommand.buildableIOSApp.<anonymous closure> (package:flutter_tools/src/commands/build_ios.dart:710:9)
<asynchronous suspension>
#10     _BuildIOSSubCommand.runCommand (package:flutter_tools/src/commands/build_ios.dart:751:33)
<asynchronous suspension>
#11     FlutterCommand.run.<anonymous closure> (package:flutter_tools/src/runner/flutter_command.dart:1558:[27](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:28))
<asynchronous suspension>
#12     AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:154:19)
<asynchronous suspension>
#13     CommandRunner.runCommand (package:args/command_runner.dart:212:13)
<asynchronous suspension>
#14     FlutterCommandRunner.runCommand.<anonymous closure> (package:flutter_tools/src/runner/flutter_command_runner.dart:496:9)
<asynchronous suspension>
#15     AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:154:19)
<asynchronous suspension>
#16     FlutterCommandRunner.runCommand (package:flutter_tools/src/runner/flutter_command_runner.dart:4[31](https://github.com/SrS2225a/custom_uploader/actions/runs/15279383478/job/42976439186#step:5:32):5)
<asynchronous suspension>
#17     run.<anonymous closure>.<anonymous closure> (package:flutter_tools/runner.dart:98:11)
<asynchronous suspension>
#18     AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:154:19)
<asynchronous suspension>
#19     main (package:flutter_tools/executable.dart:99:3)
<asynchronous suspension>

Environment

• Runner: macos-latest (macOS 14)
• Xcode: 15.4
• Flutter channel: stable (3.29.3)
• flutter-action: v2

Repro Steps (GitHub Actions)

  build_ios:
    name: Build Flutter App (iOS)
    runs-on: macos-latest
    needs: build_android  # Remove this line if you want parallel execution

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Set up Flutter
        uses: subosito/flutter-action@v2
        with:
          channel: stable
          flutter-version-file: pubspec.yaml

      - name: Get dependencies
        run: flutter pub get

      - name: Build iOS (no code signing)
        run: flutter build ios --release --no-codesign

[SrS2225a]

I wanted to give an update, I have tried running the action with older versions of x code. I even tried building using ipa instead with the same results. What can I do to fix this?

[kuhnroyal]

Is this a self hosted runner? Try looking through flutter GitHub issues if you find anything there.

[SrS2225a]

Sorry, I did not get your comment from earlier.

I am not self hosting any kind of runner. I am using githubs own ones. I did try searching in flutter project for similar issues, but all of the solutions there did not work. One did suggest to use an older version macOS in a GitHub action issue, specifically macos-13 which got me somewhere but with still no luck. It is now erroring with:

Run flutter build ipa --release --no-codesign
Synthetic package output (package:flutter_gen) is deprecated: https://flutter.dev/to/flutter-gen-deprecation. In a future release, synthetic-package will default to `false` and will later be removed entirely.

Warning: Building for device with codesigning disabled. You will have to manually codesign before deploying to device.
Unable to get Xcode project information:
 2025-06-16 21:15:16.0[7](https://github.com/SrS2225a/custom_uploader/actions/runs/15692076443/job/44209440961#step:5:8)1 xcodebuild[5501:27874] didn't find classname for 'isa' key
2025-06-16 21:15:16.075 xcodebuild[5501:27874] Writing error result bundle to /var/folders/vk/nx37ffx50hv5djclhltc26vw0000gn/T/ResultBundle_2025-16-06_21-15-0016.xcresult
xcodebuild: error: Unable to read project 'Runner.xcodeproj'.
	Reason: The project ‘Runner’ is damaged and cannot be opened. Examine the project file for invalid edits or unresolved source control conflicts.

Path: /Users/runner/work/custom_uploader/custom_uploader/ios/Runner.xcodeproj
Exception: didn't find classname for 'isa' key

No matter how I adjusted Runner.xcodeproj, it would always result in the same error. The strange part is that it continues to build fine on my actual mac with the same Runner.xcodeproj file. I am pretty sure that one is currently on macOS 13 as well, so I am not really sure what I going on here