WebGL build failure: Mono.Cecil.ResolutionException: Failed to resolve UnityEngine.Profiler

Questions & Answers
1

I’ve suddenly encountered build failures with my WebGL game on Unity 5.5.0f3. The error used to not occur with Unity 5.4.3f1, but for some reason, even when I rolled back my Unity version, I still have this error:

stdout:
SweepReport:
System.RuntimeType => Mono.Cecil.TypeDefinitionMono.Cecil.TypeDefinitionMono.Cecil.TypeDefinitionMono.Cecil.TypeDefinitionMono.Cecil.TypeDefinition
Mono.Cecil.MethodDefinition => System.Void .ctor()System.Void .ctor(System.String)System.String get_Comment()System.Void .ctor()System.Boolean get_CanTransformMultipleBlocks()
Mono.Cecil.FieldDefinition => System.String commentSystem.Func`3<System.Int32,System.Int32,System.Int32> <>f__am$cache0System.Func`3<System.Int64,System.Int64,System.Int64> <>f__am$cache1System.Func`3<System.Double,System.Double,System.Double> <>f__am$cache2System.Func`3<System.Single,System.Single,System.Single> <>f__am$cache3
Fatal error in Mono CIL Linker
Mono.Cecil.ResolutionException: Failed to resolve UnityEngine.Profiler
   at UnusedBytecodeStripper2.AddUnresolvedStubsStep.Process()
   at Mono.Linker.Steps.BaseStep.Process(LinkContext context)
   at Mono.Linker.Pipeline.Process(LinkContext context)
   at Mono.Linker.Driver.RunDriver(Driver driver, IEqualityComparer`1 typeComparer, IEqualityComparer`1 methodComparer)
stderr:

I suppose the important part here is Mono.Cecil.ResolutionException: Failed to resolve UnityEngine.Profiler.

Disabling Strip Engine Codealso doesn’t help. Any ideas on how this can be fixed? Thanks!

2

The error was caused by a DLL made obsolete by Unity 5.5.0f3. Deleting the Library folder to force a reimport of everything fixed it.