title: ORA-12514 TNS:listener does not currently know of service requested in connect descriptor in oracle 11g
body: <p>Already read all the question related to this error, but couldnt resolve the issue.</p>
  
  <p>As of yesterday, the oracle SMALLWORLD service has stopped working and the error is </p>
  
  <blockquote>
    <p>ORA-12514 TNS:listener does not currently know of service requested in connect descriptor</p>
  </blockquote>
  
  <p>the following are the system information to better understand the situation:</p>
  
  <p>LISTENER.ORA content :<a href="https://i.stack.imgur.com/n2sum.png" rel="nofollow noreferrer">Listener.ora</a></p>
  
  <p>TNSNAMES.ORA content :<a href="https://i.stack.imgur.com/vOiYH.png" rel="nofollow noreferrer">TNSNAMES.ORA</a></p>
  
  <p>SQLNET.ORA content   :<a href="https://i.stack.imgur.com/Crv2k.png" rel="nofollow noreferrer">SQLNET.ORA CONTENT</a></p>
  
  <p>the following is the result of</p>
  
  <blockquote>
    <p>LSNRCTL SERVICES</p>
  </blockquote>
  
  <p>command.</p>
  
  <p><a href="https://i.stack.imgur.com/1Edje.png" rel="nofollow noreferrer">LSNRCTL.SERVICES result</a></p>
  
  <p>as you can see the service name ATTACHMENTDB is recognisable, but service SMALLWORLD is not.</p>
  
  <p>while trying to logon with sysdba, the result is </p>
  
  <blockquote>
    <p>ORA-01017 invalid user name/password; logon denied</p>
  </blockquote>
  
  <p>while trying to logon with SYSTEM user, the result is</p>
  
  <blockquote>
    <p>ORA-01034 : ORACLE not available</p>
  </blockquote>
  
  <p>and</p>
  
  <blockquote>
    <p>ORA-27101 : shared memory realm does not exist</p>
  </blockquote>
  
  <p>below image, is the result of SQLPLUS /NOLOG command</p>
  
  <p><a href="https://i.stack.imgur.com/LIOxV.png" rel="nofollow noreferrer">SQLPLUS /NOLOG</a></p>
  
  <p>i already tried stopping and starting the ORACLE services and the Listener in the SERVICES.MSC, but nothing worked.
  i don't understand why ATTACHMENTDB service works but not the SMALLWORLD service.</p>
  
  <p>any hint appreciated.</p>