After upgrading to UE4.21, when trying to launch on iOS device I got following errors.
LogPlayLevel: [Remote] Executing build
LogPlayLevel: Setting up Mono
LogPlayLevel: Building TLM...
LogPlayLevel: 2019-01-09 05:35:44.571 defaults[1264:13408]
LogPlayLevel: The domain/default pair of (com.apple.dt.Xcode, IDEBuildOperationMaxNumberOfConcurrentCompileTasks) does not exist
LogPlayLevel: Running command : Engine/Binaries/DotNET/UnrealBuildTool.exe TLM IOS Development -deploy -SkipRulesCompile -XmlConfigCache=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/Engine/Intermediate/Build/XmlConfigCache.bin -Log=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/Engine/Programs/AutomationTool/Saved/Logs/UBT-TLM-IOS-Development_Remote.txt -Manifest=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/TLM/Intermediate/Remote/TLM/IOS/Development/Manifest.xml -Project=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/TLM/TLM.uproject -Project=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/TLM/TLM.uproject -NoUBTMakefiles -remoteini=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/TLM -skipdeploy -ini:Game:[/Script/UnrealEd.ProjectPackagingSettings]:BlueprintNativizationMethod=Disabled -NoHotReload -ignorejunk -CreateStub -NoUBTMakefiles -ImportProvision=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/TLM/Intermediate/Remote/TLM/IOS/Development/TLMDevelopment.mobileprovision -ImportCertificate=/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/TLM/Intermediate/Remote/TLM/IOS/Development/Certificate.p12 -ImportCertificatePassword=A
LogPlayLevel: Warning: WARNING: -SkipDeploy conflicts with -Deploy - ignoring
LogPlayLevel: Building UnrealHeaderTool...
LogPlayLevel: While compiling /Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/Engine/Intermediate/Build/BuildRules/UE4Rules.dll:
LogPlayLevel: (0,0) : error : Cannot open assembly '/Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/Engine/Build/BatchFiles/Mac/../../../Binaries/ThirdParty/Mono/Mac/lib/mono/4.5/mcs.exe': No such file or directory.
LogPlayLevel: Error: ERROR: Unable to compile source files.
LogPlayLevel: (see C:\Work\UnrealEngine4\Engine\Programs\AutomationTool\Saved\Logs\UBT-TLM-IOS-Development_Remote_UHT.txt for full exception trace)
LogPlayLevel: Error: Error: UnrealHeaderTool failed for target 'TLM' (platform: IOS, module info: /Users/harvey/UE4/Builds/HARVEY/C/Work/UnrealEngine4/TLM/Intermediate/Build/IOS/TLM/Development/TLM.uhtmanifest, exit code: OtherCompilationError (5)).
LogPlayLevel: [Remote] Downloading C:\Work\UnrealEngine4\Engine\Programs\AutomationTool\Saved\Logs\UBT-TLM-IOS-Development_Remote.txt
LogPlayLevel: Took 565.2822311s to run UnrealBuildTool.exe, ExitCode=7
LogPlayLevel: Error: ERROR: UnrealBuildTool failed. See log for more details. (C:\Work\UnrealEngine4\Engine\Programs\AutomationTool\Saved\Logs\UBT-TLM-IOS-Development.txt)
LogPlayLevel: (see C:\Work\UnrealEngine4\Engine\Programs\AutomationTool\Saved\Logs\Log.txt for full exception trace)
LogPlayLevel: AutomationTool exiting with ExitCode=7 (7)
LogPlayLevel: Completed Launch On Stage: Build Task, Time: 568.950702
LogPlayLevel: BUILD FAILED
PackagingResults: Error: Deployment failed! Unknown Error
Besides UE, I’ve also upgraded my remote MacOS to Mojave and XCode to 10.1.
It’s seems that there is missing some files related to Mono third party, but there is it supposed to be?