Oracle XE stopped working. TNS listener refused connection

Question

I'm working on an application which uses Oracle XE 11g as its RDBMS. It was working for several weeks but now I started to get an error message about the connection being refused.

I restarted my system but it did not help. I uninstalled XE, deleted all remaining files (even from registry) and reinstalled it. Now I get another error message:

Listener refused the connection with the following error: ORA-12505, TNS:listener does not currently know of SID given in connect descriptor

I've read about this error and others suggested adding a new SID to the listener.ora file:

(SID_DESC =
  (SID_NAME = XE)
  (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
)

If I do this I get another error message:

ORA-01034: ORACLE not available ORA-27101: shared memory realm does not exist

My configuration files are: listener.ora

    SID_LIST_LISTENER =   (SID_LIST =
    (SID_DESC =
      (SID_NAME = XE)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
    )
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
      (PROGRAM = extproc)
    )   )

LISTENER =   (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = AAROLD.in.mycompany.com)(PORT = 1521))
    )   )

DEFAULT_SERVICE_LISTENER = (XE)

tnsnames.ora

XE =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = AAROLD.in.mycompany.com)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = XE)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

ORACLR_CONNECTION_DATA = 
  (DESCRIPTION = 
    (ADDRESS_LIST = 
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) 
    ) 
    (CONNECT_DATA = 
      (SID = CLRExtProc) 
      (PRESENTATION = RO) 
    ) 
  ) 

lsnrctl status returns with:

LSNRCTL for 32-bit Windows: Version 11.2.0.2.0 - Production on 19-M┴RC. -2013 15:12:24

Copyright (c) 1991, 2010, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for 32-bit Windows: Version 11.2.0.2.0 - Production
Start Date                19-M┴RC. -2013 15:01:12
Uptime                    0 days 0 hr. 11 min. 11 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Default Service           XE
Listener Parameter File   C:\oraclexe\app\oracle\product\11.2.0\server\network\admin\listener.ora
Listener Log File         C:\oraclexe\app\oracle\diag\tnslsnr\AAROLD\listener\alert\log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1ipc)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=AAROLD.in.mycompany.com)(PORT=1521)))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
  Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully

Do you have any idea what can be the problem? I'm not an Oracle expert so I'm completely in the dark here.

Answer 1

I had the exact same problem and after spending almost 4 hours trying to find and answer, finally adding

(SID_DESC =
  (SID_NAME = XE)
  (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
)

to my listener.ora and restarting both XE services solved the issue. I am using 11.2.0 (XE) on windows 7 x64 with out any hitch till yesterday. A reboot of my PC this morning caused the listener to not find the SID.

Now I am backing up both listener.ora and tnsnames.ora.

btw, forgot to mention I changed the hostname in both the files from bob.mycompany.com to localhost.

Answer 2

On Windows 7 64 bit, Orcale XE 11 my OracleXXETNSListener service was not running and did terminate immediately when I tried to start it.

1. Adding

(SID_DESC = (SID_NAME = XE) (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server) )

to my

C:\oraclexe\app\oracle\product\11.2.0\server\network\ADMIN\listener.ora

2. changing the hostname to localhost

3. restarting the OracleServiceXE service under System - Services solved the issue.

So the complete listener.ora section looks like:

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\servers\oraclexe\app\oracle\product\11.2.0\server)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\servers\oraclexe\app\oracle\product\11.2.0\server)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = XE)
      (ORACLE_HOME = C:\servers\oraclexe\app\oracle\product\11.2.0\server)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
  )

DEFAULT_SERVICE_LISTENER = (XE)

Update: Now it is 5 years later and I had the same issue with OracleXE 18c on Win10. The TNS listener would not start right after successful installation because oracleXE\dbhomeXE\NETWORK\ADMIN\listener.ora was pointing to localhost.docker.internal instead of localhost.