Warning: no filemap entries available

The following warning occurs while doing opatch lsinventory:
"Warning: no filemap entries available"

Cause:
$ORACLE_HOME/inventory/oneoffs//etc/config/actios or $ORACLE_HOME/inventory/oneoffs//etc/config/inventory does not exist.

Solution:
1. Download the failed patch.
2. Unzip the downloaded patch.
3. cd /etc/config
4. cp inventory $ORACLE_HOME/inventory/oneoffs/<patch number>/etc/config
5. cp actions $ORACLE_HOME/inventory/oneoffs/<patch number>/etc/config
6. Run 'opatch lsinventory' again to verify the result.

Please note this is to fix an issue where "opatch lsinventory" lists an already installed patch this way