WaitAll for multiple handles on a STA thread is not supported

Question

1. Why do I get this error message? \"WaitAll for multiple handles on a STA thread is not supported.\"
2. Should I use [MTAThreadAttribute] attribut? Update

Answer 1

Actually I use the following to replace WaitHandle.WaitAll(doneEvents);

foreach (var e in doneEvents)
    e.WaitOne();