Symptoms
This article discusses a code bug in the vector file that causesa”System.NullReferenceException” exception and discusses how to resolve this bug.
Resolution
When you call the pop_back method of the vector<bool> template class to delete the last element that is stored in a vector<bool> template class object, you receive the following error message:

An unhandled exception of type ‘System.NullReferenceException’ occurred in ApplicationName
Additional information: Object reference not set to an instance of an object.Note ApplicationName is a placeholder for the executable (.exe) file name of your program.