title: How to fix Linked Server from SQL Server 2016 to Oracle 12c?
body: <p>I set up a few weeks ago a linked server in my sql server 2016 to my oracle 12c following <a href="https://logicalread.com/sql-server-2014-and-oracle-12c-linked-servers-mo01/#.WW4pR4jyuUl" rel="nofollow noreferrer">this guide</a>. It was working properly, but after some windows updates that restarted my machine, it no longer works. I can log into oracle properly through sqlplus and sql developer, but not through sql server. I get the following error:</p>
  
  <pre><code>OLE DB provider "OraOLEDB.Oracle" for linked server "LINKED_ORACLE" returned message "ORA-12154: TNS:could not resolve the connect identifier specified".
  Msg 7303, Level 16, State 1, Line 1
  Cannot initialize the data source object of OLE DB provider "OraOLEDB.Oracle" for linked server "LINKED_ORACLE".
  </code></pre>
  
  <p>I restarted the SQL Server service, as well as restarted windows again, but still same error. What could have changed in a single restart? How can I fix it and get the linked server working again?</p>