An unprotected read access of the variable _errMsg from MigrationDestinationManager at the destructor of MoveTimingHelper, can be concurrent with write accesses, e.g. MigrationDestinationManager::_setStateFail or MigrationDestinationManager::_setStateFailWarn. 

An implementation idea is to create a copy of the _errMsg protected by the mutex when instantiating a MoveTimingHelper, and not passing an unprotected pointer.