Today, I saw the following message on my Domino console

[0E88:005A-0FF4] 08.03.2016 17:19:01   The database d:\Domino\data\mail\ukrause.nsf was unable to open or read the file d:\DAOS\0002\97FC43BEED143800A6608E557BE888498DB9BC5100015B7C.nlo: File truncated – file may have been damaged

If you see such a message in your production environment, you should immediately find out

• what causes the damage?
• which note does the .nlo belong to?

In my case, the answer for the first one is: Anti Virus Software.

And here is, how I found the answer to the second on

If not already in place, set

DEBUG_DAOS_DIAGNOSTICS=1

Next trigger a console command

tell daosmgr LISTNLO MAP -V mail/ukrause.nsf

This will create a file listNLO.txt in you Domino data directory

Open the file and search for the .nlo file in question

68258,0X10AA2,69422,0X10F2E,88956,88956,DAOS,

97FC43BEED143800A6608E557BE888498DB9BC5100015B7C,

0X8,VALID,ö1,97FC43BEED143800A6608E557BE888498DB9BC5100015B7C,[0:1],97FC43BEED143800A6608E557BE888498DB9BC5100015B7C,[0:1],Shared,1

You now have the noteId of the document that has a ticket to the damaged .nlo.

Use your favorite tool to find and open the document.

In my case, it was just a SPAM mail. So no worries. But if this happens in production, you should now go and find the ( hopefully intact ) nlo in your backup and restore it.