ORA-21561 : OID generation failed

The error below may happen also during creation of a new database.
The problem is that /etc/hosts is not properly configured (usually  It does not contain an entry for the name of the server )

Connection Via 10.2.0.3 SQL*Net Fails With Error ORA-21561: OID Generation Failed [ID 559981.1]

Applies to:

Oracle Net Services - Version: 10.1.0.3.0 to 10.2.0.4.0
Information in this document applies to any platform.
Checked for relevance on 14-JAN-2010.

Symptoms

 After upgrading to version 10.2.0.3, SQL*Plus connections fail with the following error:
ORA-21561 : OID generation failed
e.g.
-bash-2.05b$ sqlplus username/password@tns_connect_string

SQL*Plus: Release 10.2.0.3.0 - Production on Fri Mar 7 16:15:10 2008

Copyright (c) 1982, 2006, Oracle. All Rights Reserved.

ERROR:
ORA-21561 : OID generation failedEnter user-name: <username>/<password> @ <tns connect string>
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning and Data Mining options

SQL>

Changes

It is likely that a recent upgrade to 10.2.0.3 has taken place.

Cause

Incorrect /etc/hosts mapping for the client machine or no mapping at all. 

Solution

Check the client's /.../hosts file and verify that the local node is correctly identified with a mapping for both the short and fully qualified name of the host.