Ora-12560: TNS: protocol adapter error
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Make sure that you have set the correct ORACLE_SID:
C:\>sqlplus system/manager@orcl
SQL*Plus: Release 11.2.0.2.0 Production
ERROR:
ORA-12560: TNS:protocol adapter error
Enter user-name:
C:\>set ORACLE_SID=orcl
C:\>sqlplus system/manager@orcl
Connected to:
Oracle Database 11g Express Edition Release 11.2.0.2.0 - Production
SQL> startup
ORACLE instance started.
Total System Global Area 1071333376 bytes
Fixed Size 1388352 bytes
Variable Size 620757184 bytes
Database Buffers 444596224 bytes
Redo Buffers 4591616 bytes
Database mounted.
Database opened.
SQL>
If the above method doesn’t work, may be the OracleService for the database is not running. Check for the service, if it is not running then starts the service. If it is running then restart the service.
C:\>sqlplus
SQL*Plus: Release 11.2.0.2.0 Production on Sat Dec 17 22:34:24 2016
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Enter user-name: / as sysdba
ERROR:
ORA-12560: TNS:protocol adapter error
Now restart the service using below method.
Start > Run > Type Services.msc
Start/Restart both Oracle service & listener service- OracleServiceORCL & OracleorclTNSListener
C:\>sqlplus
SQL*Plus: Release 11.2.0.2.0 Production on Sat Dec 17 22:41:30 2016
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Enter user-name: / as sysdba
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 1071333376 bytes
Fixed Size 1388352 bytes
Variable Size 620757184 bytes
Database Buffers 444596224 bytes
Redo Buffers 4591616 bytes
Database mounted.
Database opened.
SQL>