IOS build error

The app works perfectly at design time but when I try to build I get this error…

Thanks in advance!

Failed running /Applications/Unity/Unity.app/Contents/Tools/UnusedByteCodeStripper2/UnusedBytecodeStripper2.exe --api NET_2_0_Subset -out “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/Managed/tempStrip” -l none -c link -b true -x “/Applications/Unity/PlaybackEngines/iOSSupport/Whitelists/Core.xml” -f “/Applications/Unity/Unity.app/Contents/il2cpp/LinkerDescriptors” -x “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/Managed/…/platform_native_link.xml” -x “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/methods_pointedto_by_uievents.xml” -x “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/preserved_derived_types.xml” -x “/Users/mudo/Desktop/YincanYDemos/Assets/link.xml” -x “/Users/mudo/Desktop/YincanYDemos/Assets/Prefabs/Destroyer/link.xml” -d “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/Managed” -a “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/Managed/Assembly-CSharp.dll” -a “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/Managed/Assembly-UnityScript.dll” -a “/Users/mudo/Desktop/YincanYDemos/Temp/StagingArea/Data/Managed/UnityEngine.UI.dll”

stdout:
Fatal error in Mono CIL Linker
System.ArgumentException: Unable to find the file for the assembly named ‘Qualcomm.Vuforia.UnityExtensions, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null’ specified in link file ‘/Users/mudo/Desktop/YincanYDemos/Assets/Prefabs/Destroyer/link.xml’. Should this assembly be in the project? Use the ‘ignoreIfMissing=“1”’ attribute if this assembly may not always exist. —> Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: ‘Qualcomm.Vuforia.UnityExtensions, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null’
at Mono.Linker.LinkContext.Resolve (Mono.Cecil.IMetadataScope scope) [0x00047] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Steps.ResolveFromXmlStep.GetAssembly (Mono.Linker.LinkContext context, Mono.Cecil.AssemblyNameReference assemblyName) [0x00001] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Steps.ResolveFromXmlStep.ProcessAssemblies (Mono.Linker.LinkContext context, System.Xml.XPath.XPathNodeIterator iterator) [0x00014] in <8288c42737d44a4799e8c99e6e64112b>:0
— End of inner exception stack trace —
at Mono.Linker.Steps.ResolveFromXmlStep.ProcessAssemblies (Mono.Linker.LinkContext context, System.Xml.XPath.XPathNodeIterator iterator) [0x00104] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Steps.ResolveFromXmlStep.Process () [0x0002b] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Steps.BaseStep.Process (Mono.Linker.LinkContext context) [0x00018] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Pipeline.Process (Mono.Linker.LinkContext context) [0x00019] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Driver.Run (System.Collections.Generic.IEqualityComparer1[T] typeComparer, System.Collections.Generic.IEqualityComparer1[T] methodComparer) [0x003e2] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Driver.RunDriverWithErrorHandling (Mono.Linker.Driver driver, System.Collections.Generic.IEqualityComparer1[T] typeComparer, System.Collections.Generic.IEqualityComparer1[T] methodComparer) [0x00001] in <8288c42737d44a4799e8c99e6e64112b>:0
at Mono.Linker.Driver.RunDriver (Mono.Linker.Driver driver, System.Collections.Generic.IEqualityComparer1[T] typeComparer, System.Collections.Generic.IEqualityComparer1[T] methodComparer) [0x00002] in <8288c42737d44a4799e8c99e6e64112b>:0
stderr:

UnityEngine.Debug:LogError(Object)
UnityEditorInternal.Runner:RunManagedProgram(String, String, String, CompilerOutputParserBase, Action1) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildUtils.cs:96) UnityEditorInternal.AssemblyStripper:RunAssemblyLinker(IEnumerable1, String&, String&, String, String) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:102)
UnityEditorInternal.AssemblyStripper:StripAssembliesTo(String[ ], String[ ], String, String, String&, String&, String, IIl2CppPlatformProvider, IEnumerable1) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:95) UnityEditorInternal.AssemblyStripper:RunAssemblyStripper(String, IEnumerable, String, String[ ], String[ ], String, IIl2CppPlatformProvider, RuntimeClassRegistry) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:201) UnityEditorInternal.AssemblyStripper:StripAssemblies(String, IIl2CppPlatformProvider, RuntimeClassRegistry) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:126) UnityEditorInternal.IL2CPPBuilder:Run() (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:143) UnityEditorInternal.IL2CPPUtils:RunIl2Cpp(String, String, IIl2CppPlatformProvider, Action1, RuntimeClassRegistry, Boolean) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:34)
UnityEditor.HostView:OnGUI()

The error message is pretty informative actually:

The link.xml file specifies (to the code stripper) which assemblies it should keep. An assembly that is listed in /Users/mudo/Desktop/YincanYDemos/Assets/Prefabs/Destroyer/link.xml cannot be found, hence the error.

You should follow the instructions in the error mesage (add the attribute) or remove that assembly from the link.xml file altogether.