I just started to updated Lotus Domino 8.5 on my Debian Server to Lotus Domino 8.5.1 and during the update from debian itself it shows:

W: GPG error: http://security.debian.org lenny/updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9AA38DCD55BE302B
W: There is no public key available for the following key IDs:
9AA38DCD55BE302B
W: You may want to run apt-get update to correct these problems

Even after running apt-get update, it won´t solve the problem.

To fix this “no public key available” problem, follow the steps below:

1. Go your shell and type (you need to be root):
   

   apt-get install debian-keyring debian-archive-keyring

2. Once debian-keyring and debian-archive-keyring are installed/updated, you now could update your debian system without error messages. To update your debian system perform the following steps:

3. apt-get update

4. apt-get upgrade

After that the "There is no public key available for the following key IDs" will not be shown again.