ORA-12560:TNS:Protocol adapter error in OracleService ORCL is still running
<p><a href="https://i.stack.imgur.com/GSMJV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GSMJV.png" alt="enter image description here"></a></p>

<p>I use <code>sqlplus</code> to try to connect <code>/ as sysdba</code>.</p>

<p>I tried to set <code>oracle_sid=ORCL</code>, but it's not better. </p>

<p>I Google[d] for this error but not able to find the actual reason and how to solve this error ?</p>

<blockquote>
  <p>ORA-12560: TNS:protocol adaptor error </p>
</blockquote>

<p>Can anyone tell me a perfect solution to solve login problem.</p>