Not sure about exact repro. Sometimes when I open a test with coded steps in Visual Studio I get the following error when I try to run it: '17-Dec-16 11:23:32 PM' - System.ArgumentException: String cannot have zero length. at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type) at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase) at System.Reflection.Assembly.GetType(String name) at ArtOfTest.WebAii.Design.Execution.ExecutionUtils.EnsureTypeExists(Assembly assm, String typeName) at ArtOfTest.WebAii.Design.Execution.ExecutionUtils.CreateCodedTestInstance(Test test, TestResult result, String binariesFolder) at ArtOfTest.WebAii.Design.Execution.ExecutionEngine.InternalExecuteTest(Test test, TestResult initializationResult) at ArtOfTest.WebAii.Design.Execution.TestExecuteProxy.ExecuteTest(ExecuteTestCommand command) Closing the test, rebuilding and opening it again seems to work. But I think this same issue also causes problems when the test suite is deployed on remote machines.