null
. The examples provided expose various cases where this error arises, together with some recommendations on how to mitigate the error.
The dreaded and often asked "Error 1009: Cannot access a property or method of a null object reference" is a signal that some of the data appears null, but is tried to be used as a populated object. There are pretty many types of issues that can cause this behavior, and each one should be tested against the code where the error arised.