To cancel an index update using IIndexStatusHandler, return AbortValue.Cancel or AbortValue.CancelImmediately from your CheckForAbort function. AbortValue.Cancel causes the update to stop after the current file and to commit data indexed so far. AbortValue.CancelImmediately cancels the update immediately, without saving any changes to the index (so the index will revert to its state as of the last commit).

Each time IIndexStatusHandler.OnProgressUpdate is called, the IndexProgressInfo.UpdateType will indicate the reason for the notification. The UpdateType is a MessageCode value that indicates when, for example, a file was successfully indexed (dtsnIndexFileDone) or could not be indexed due to an error (dtsnIndexFileOpenFail, dtsnIndexFileEncrypted).