How can I find invalid (false or non-existent) documents?

When a Parent document has responses, it keeps track of the all the response documents in the nd.Responses property (which refers to the collection or list of response documents). The collection of response documents for the parent can change over time (responses are created or deleted), and usually this is updated correctly in the nd.Responses property.

But, sometimes in Notes (for whatever reason) this is not always true, for example: nd.Responses "thinks" it has 5 response documents in its collection, but there are actually only 4 response documents that exist (i.e. a document was deleted but was not updated in the collection list).

scanEZ has the Documents Analyzer, which can display all occurrences of non-existing response document. Go to: Tools > Documents Analyzer, and use the checkbox which reads: Document has responses, but response is missing

scanEZ simply shows what is in the database, so if you are looking at the Parent document it will "say" that there are 5 documents, but at the same time show that one of them is invalid or non-existent. Trying to copy/delete an invalid response document, will not work, since it does not exist! (even though it has a NoteID, it just refers to a document that does not exist anymore).

So how can you correct this? In Notes, you can try to perform a "Compact" action on the database, this may help clean up some of the unnecessary data (invalid docs) in your database, or run a "fixup" task on your server, or try to make a new replication of your database (Notes has some filters which may help clean up a database), but none of these is guaranteed to work. This is actually a common problem/occurrence that Notes experiences, and it is found throughout all versions 4.6 to 7.x, there are even discussions about this topic on the Notes.net forums.