Exceptions inside 'delete' method (void return)

With me using protobuf it’s a bit more difficult to view the raw response, the headers I receive are:

Access-Control-Allow-Headers: Content-Type, Authorization
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, PATCH, OPTIONS
Access-Control-Allow-Origin: *
Content-Type: application/x-protobuf
Date: Fri, 12 Oct 2018 14:59:33 GMT
Set-Cookie: ss-id=FttbMHxxD4MhJYaIRGq7; path=/; samesite=lax; httponly
Set-Cookie: ss-pid=baOnHwbr3ug456GYYBL2; expires=Tue, 12 Oct 2038 14:59:33 GMT; path=/; samesite=lax; httponly
Transfer-Encoding: chunked
Vary: Accept
X-Powered-By: ServiceStack/5.40 NetCore/OSX

The data I can glean from the response is:

InternalServerErrorùServiceStack.HttpError: Failed to execute!
at ***.Service.Delete(DeleteUser request) in *****:line 243œ[DeleteUser: 10/12/2018 14:59:34]:
[REQUEST: {id:3}]
ServiceStack.HttpError: ServiceStack.HttpError: Failed to execute!
at ***.Service.Delete(DeleteUser request) in ***:line 243
at ***.Service.Delete(DeleteUser request) in ***:line 285
at lambda_method(Closure , Object , Object )
at ServiceStack.Host.ServiceExec1.<>c__DisplayClass3_0.<CreateExecFn>b__0(Object service, Object request) at ServiceStack.Host.ServiceRunner1.ExecuteAsync(IRequest req, Object instance, TRequest requestDto)

It’s all quite odd, doing some further testing, I’m seeing the 500 errors on PUT and DELETE, however GET and POST work fine.