ORA-12545: Connect failed because target host or object does not exist

Have anyone encounter this error before? I tried to refer to this link: http://www.ardentperf.com/2007/04/02/local_listener-and-ora-12545/

But it doesn't really resolve o开发者_开发技巧ur issue. Our scenario is that we are able to connect to the database however we will encounter this error when we try to select data from a view.

I have enabled Client-side sqlnet trace but i am unable to interpret what is the exact cause of the issue.

Any ideas anyone?

Thanks

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For me the problem was the HOST was not being detected by name in the TNSNAMES.ora, using the IP address instead resolved it (I think its due to a domain controller issue):

XYZD =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 123.45.67.89)(PORT = 1521))
    (CONNECT_DATA = (SERVICE_NAME = XYZD))
  )

Do a command: “ping HOST” to find the servers IP address.

• PING HOST
• TELNET HOST PORT
• TNSPING TNS_ALIAS

Edit:

Just ran into this again, this time it was a Firewall blocking TCP via the port.

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This issue can be multiple things:

1. Your TNSNAMES.ora isn't up to date

Fix: Find your Oracle Home Find Directory: /network/ADMIN/

TNSNAMES.ora should be in there if you're experiencing this issue on a local machine

2. Create TNS_ADMIN Environmental Variable

In my case:

Variable Name: TNS_ADMIN

Value: C:\Programs\Ora10g\network\ADMIN

For testing purposes, try connecting to the Oracle DB using sqlplus (you may already be trying this).

---

I also had this issue, and since I was not using a tnsnames.ora file, I almost gave up hope, when I stepped on this link.
So, now my code looks like this:

import cx_Oracle 
connection_string = '''username/password@(DESCRIPTION=
                                            (ADDRESS_LIST=
                                                (ADDRESS=
                                                    (PROTOCOL=TCP)
                                                    (HOST=<host_name>)
                                                    (PORT=<port_numer>)
                                                )
                                            )
                                            (CONNECT_DATA=
                                                (SID=<your_SID>)
                                            )
                                        )'''
db = cx_Oracle.connect(connection_String)

Now you can create a cursor and write your query.
Note: This is not a recommended practice, but I used it just for testing.