H:\>sqlplus produser@proddb

SQL*Plus: Release 10.2.0.3.0 - Production on Mon Oct 26 13:58:12 2009

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

Enter password:
ERROR:
ORA-28030: Server encountered problems accessing LDAP directory service

My sqlnet.ora and ldap.ora shows the following:

sqlnet.ora

NAMES.DIRECTORY_PATH= (LDAP, TNSNAMES)

ldap.ora

DIRECTORY_SERVERS= (oid1p.iam.com:389:636,oid2p.iam.com:389:636,oid3p.iam.com:389:636)

DEFAULT_ADMIN_CONTEXT = "dc=iam,dc=com"

DIRECTORY_SERVER_TYPE = OID

I couldn't figure out what was going on.  Every userid that was idnetified GLOBALLY was having this same error message:

Enter password:
ERROR:
ORA-28030: Server encountered problems accessing LDAP directory service

I was able to login to other remote servers from the database server using ldap entries.  Didn't make sense. 

Finally after numerous attempts, this is what I did to fix it.   I had started up the database with the wrong ORACLE_BASE set.  It was set to following :   ORACLE_BASE=/oracle     It should have been set to :  ORACLE_BASE=/u01/oracle

Then I shutdown and restart the database and the user was able to login.    The reason why this was the issue was because the wallet was under /u01/oracle/admin/<sid>/wallet directory and it couldn't find it.

Now you can also set something similar in your sqlnet.ora if possible so you prob. don't have to restart your database:

WALLET_LOCATION= 
  (SOURCE=
      (METHOD=file)
      (METHOD_DATA= 
         (DIRECTORY=/u01/oracle/admin/wallets)))

You can also run this command to check if your wallet is open:

select * from system.is_wallet_open;

You'll get something like :

WALLET_STATUS
-------------
            1

Hope this helps.

Thanks,