Resolving ORA-12705 on Client

This tip resolves Oracle client error: “ORA-12705: Cannot access NLS data files or invalid environment specified“. According to Oracle documentation, “ORA-12705 can happen under the following conditions:

1. ORA-12705 with incorrect NLS_LANG parameter
2. ORA-12705 with incorrectly specified ORA_NLSx
3. ORA-12705 from incorrect Oracle install or configuration
4. ORA-12705 when using Special Character sets
5. ORA-12705 when connecting with SQL*Net
6. ORA-12705 during migrations
7. ORA-12705 when connecting with SQL*Plus
8. ORA-12705 when connecting with language pre-compilers
9. ORA-12705 during Export/Import

Try doing the following to fix this error on the client side. On the client Windows machine (this tip is only for Windows), The NLS_LANG must be unset in the Windows registry (re-naming works the best because you know what you changed). Look for the NLS_LANG subkey in the registry at \HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE, and rename it. Then try SQLPlus again.