ORA-12541: TNS: no listener

Does anybody know what can cause this error message (ORA-12541: TNS: no listener)? The only answer I find in all Oracle books (Net8 Administrator's Guide, etc.) is check your listener if it's started & try your test again. My listener is started (WinNT-Services).
What I am trying to do is to configure a net service name so I can use my OEM. So, I use Net8 Configuration Assistant, enter all the needed parameters (they are consistent with my TSNNAMES.ORA & LISTENER.ORA) - when I choose to perform a test I get this error message.
I also performed a loopback test through Net8 Assistant as they suggest in Net8 Administrator's Guide - I get the same error.
Please somebody help me with this issue - I've been trying everything. I uninstalled Oracle 8.1.6 & installed 8.1.7 - same result.

Thanks for your help!

1. Compare text Listener.ora and tnsnames.ora files.
They place in:
$ORACLE_HOME/network/admin - directory
and
they should be something like this:

---------------- LISTRNER.ORA ----------------------------
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = YOUR_HOST_NAME or IP ADDRESS)(PORT = 1521))
)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
)
)
)

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = c:\orant)
(PROGRAM = extproc)
)
(SID_DESC =
(GLOBAL_DBNAME = YOUR_HOST_NAME or IP ADDRESS)
(ORACLE_HOME = c:\orant)
(SID_NAME = YOUR_SID)
)
)

check is correct : YOUR_HOST_NAME or IP ADDRESS
check is correct : YOUR_SID

---------------- TNSNAMES.ORA ----------------------------

YOUR_SERVICE_NAME =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = YOUR_HOST_NAME or IP ADDRESS)(PORT = 1521))
)
(CONNECT_DATA =
(SID_NAME = YOUR_SID)
# or
# (SERVICE_NAME = YOUR_SERVICE_NAME)

)
)

EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
)
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
)
)

check is correct : YOUR_SERVICE_NAME
check is correct : YOUR_HOST_NAME or IP ADDRESS
check is correct : YOUR_SID
-----------------------------------------------------------
if need then correct your parameters.

2. Check haw work LISTENER manually:

- open command prompt window
- enter command:

lsnrctl
..
> status
check is status correct and then:

> reload (if you change any parameter in listener.ora)

you can do simple:

> stop
> start
> status

...
> exit

3. check sqlnet connection:

in command line prompt: tnsping YOUR_SERVICE_NAME
if you have any domain name then check file
sqlnet.ora

for example:
NAMES.DEFAULT_DOMAIN = YUOR.DOMAIN
NAMES.DIRECTORY_PATH= (TNSNAMES)

------------------------------------------------------
Good luck! Olga K.

You ahve more then one tnsnames.ora file, Make sure in all of your Tnsnames.ora file have the entry of the instance you are trying to connect.

Shestakov has given the correct solution. Here is an excerpt from the Oracle Documentation:

Quote:

---

TNS-12541 TNS:no listener

Cause: The connection request could not be completed because the listener is not running.

Action: Ensure that the supplied destination address matches one of the addresses used by the listener. Compare the TNSNAMES.ORA entry with the appropriate LISTENER.ORA file (or TNSNAV.ORA if the connection is to go by way of an Interchange). Start the listener on the remote machine.

---

DEAR FRIEND MR.Shestakov,

THANKS AGAIN FOR ALL YOUR INPUT.
1) I ALREADY MADE SURE THAT BOTH OF THESE FILES ARE CONSISTENT WITH EACH OTHER: BOTH OF THEM HAVE ACCURATE - YOUR_SERVICE_NAME, YOUR_HOST_NAME, IP ADDRESS, YOUR_SID.
2) THE ONLY THING IS - ONE OF THEM (I CAN'T REMEMBER NOW WHICH ONE) HAS 2 SEPARATE ENTRIES: ONE FOR PORT 1521 & ANOTHER ONE FOR SOME OTHER PORT.
3) I MANUALLY CHECKED, STOPPED & STARTED AGAIN MY LISTENER. STATUS CHECK "WENT WELL" TOO.
4) WHEN I DO: tnsping YOUR_SERVICE_NAME - I GET THE SAME ERROR MESSAGE BUT WITH TNS- PREFIX (TNS-12541).
BUT I AM ABLE TO : PING YOUR_HOST.
5) SQLNET.ORA: AT SOME POINT WHEN I WAS TRYING SOME UTILITIES THEY SUGGEST IN NET8 ADMIN'S GUIDE - I HAD ORACLE ERROR MESSAGES ABOUT THIS FILE:

NNL-00024: WARNING: NO PREFERRED NAME SERVERS IN SQLNET.ORA
NNL-00018: WARNING: COULD NOT CONTACT DEFAULT NAME SERVER.

SO I LOOKED AT THAT FILE - IT ONLY HAS 2 GENERIC LINES OF CODE IN IT & NONE OF THEM HAS ANY SPECIFIC NAMES OR MY PC PARAMETERS. AND I AM NOT SURE WHAT IS SUPPOSED TO BE IN IT.

CAN YOU HELP?

THANKS A LOT!

OLGA.

Are you doing the TNSPING on that machine or a client machine? If it is a client machine, is the tnsnames.ora up do date with the correct information, IP of the server that the Oracle is listening on?

Often I've seen this error caused by machines with 2 NIC's where the listener is listening on one IP and the tnsnames.ora is pointing to the hostname of the machine (which is not the correct IP for the listener).

And does anyone know how to turn of the centering for all these messages?

OK, it's good.

Then we try to check default domain information in sqlnet.ora and init.ora files.

In file SQLNET.ORA check following lines:

NAMES.DEFAULT_DOMAIN = your.domain
# for example org_name.com

NAMES.DIRECTORY_PATH= (tnsnames, onames, hostname)

and check in init.ora, tnsnames.ora, listener.ora:

------- INIT.ORA ----------------
You have something like this:

db_name = "YOUR_DB"
db_domain = your.domain.com
instance_name = YOUR_SID
service_names = YOUR_SID.your.domain

--------- TNSNAMES.ora ------------------
...
(service_name = YOUR_SID.your.domain)
...
# full service name

NOTE: try setup full entry name:

YOUR_ENTRY.your.domain =
( DESCRIPTION = ...

----------------------------------------------------
May be try to check IP_ADDRESS directly in:
... (ADDRESS = (PROTOCOL = TCP)(HOST = 111.222.333.444 )(PORT = 1521))
if you know it.
----------------------------------------------------

after each correction try execute TNSPING your_entry and
TNSPING your_entry.your.domain

could you post the tnsnames.ora and listener.ora and sqlnet.ora files. Remember to mask any IP/Hostname information. Please leave the port information as it is....

Looking forward to see... BTW, may I know the relase date for this 8.1.7 package...

Sam

I think my problem is in sqlnet.ora. It only has 2 lines in it:

NAMES.DEFAULT_DOMAIN = your.domain
NAMES.DIRECTORY_PATH= (tnsnames, onames, hostname)

just exactly the way they are typed in above. It seems to me that I need to change it - but I was not sure what to use for tnsnames & onames.

I will post my tnsnames.ora & listener.ora & sqlnet.ora files tomorrow. I will have access to that machine only tonight.

Thanks,
Olga.

Comment:

tnsnames Local Naming
Net service names are resolved using the tnsnames.ora file which resides on the client.

onames Oracle Names
Net service names and database service names are resolved centrally through an Oracle Names server.

hostname Host Naming
Net service names are resolved using the host naming method. Certain criteria must be met to use host naming.

Volla!!

Now you have two options... In your sqlnet.ora file, specify the domain name as it had been specified in the tnsnames and try.

example say your tnsnames is to say

orcl1.xyz.com= (....)


in your sqlnet.ora file specify

NAMES.DEFAULT_DOMAIN = xyz.com


Second option is, just comment the NAMES.DEFAULT_DOMAIN

and try....

One of the above should work.

Sam

Your port numbers have to be the same in both your TNSNAMES entries and your LISTENER.ORA.

If your listener is listening on port 1521 and the tnsnames is trying to contact port 1526 or any other port number besides 1521 you will get a NO LISTENER error

Try that.

Thank you everybody for all your help - I finally got it to work!

I believe that it could be just a minor mistake when configuring the Oracle .
1. Have you startup Oracle Agent Service if you want to use
OEM ?
2. Can you use tnsping in your client machine to test the connection ?