Why does the indexer failure message delay with the authentication code sometimes, and how to retrieve the authentication code?

Question

I have a Web App that uses data I have on a SharePoint site, to allow users to ask questions about. Sometimes when I run my indexer, after loading new data files on my SharePoint site, the process will fail and it will show me the failure on my screen. I can then retrieve the authentication code and use it to log in, then rerun the indexer and it works fine.

Other times, it will fail, but the failure does not show up on my screen until after the authentication code expires and it does not allow me to run the indexer.

When it fails to show up on my screen, where can I go look for the authentication code other than on the application screen under the indexer?