ORA-12557: TNS:protocol adapter not loadable

this problem On windows Platforms .

and it must be related to Windows Environment or Oracle Home PATH because sqlplus command works smoothly when I execute it inside ORACLE_HOME\bin.

RUN: SYSDM.CPL to open Windows System Properties
Click on Advanced Tab > Environment Variables…

Click the Path variable under System Variable, then click  Edit…

change the order between Oracle Client Home and Oracle DB Home:

From: D:\oracle\product\10.2.0\client_1\bin;D:\oracle\product\10.2.0\db_1\bin;

To: D:\oracle\product\10.2.0\db_1\bin;D:\oracle\product\10.2.0\client_1\bin;

in other words, put the Oracle DB Home in front of the other path.

Or i Don’t love this way , Since its not actual solution but its solve problem sometimes :
1-Remove ORACLE_HOME From environment Variable .

2- Restart PC 

Osama mustafa