ORA-12557: TNS:protocol adapter not loadable


Sometimes You can get “ORA-12557: TNS:protocol adapter not loadable ” error.


Details of error are as follows.

ORA-12557: TNS:protocol adapter not loadable

Cause: On some platforms (such as OS/2) protocol adapters are loaded at run-time. If the shared library 
(or DLL) for the protocol adapter is missing or one of its supporting libraries is missing then this error is returned.
Action: For further details, turn on tracing and reexecute the operation. The trace file will include the 
name of the shared library (or DLL) that could not be loaded.




This error is related with the TNS_ADMIN and bin directory are different in PATH  variable for Windows.
To solve this error, add TNS_ADMIN directory to the PATH variable on windows then save it and try it again.

Check PATH variable in Windows



Check PATH variable in Linux/Unix

echo $PATH


Or This error is caused by  32 bit application with 64 bit database, so try to use same client version for 64 bit database.


Or Check your Oracle Home and Oracle SID if they are set correctly or not.



Do you want to learn more details about RMAN, then read the following articles.



About Mehmet Salih Deveci

I am Founder of SysDBASoft IT and IT Tutorial and Certified Expert about Oracle & SQL Server database, Goldengate, Exadata Machine, Oracle Database Appliance administrator with 10+years experience.I have OCA, OCP, OCE RAC Expert Certificates I have worked 100+ Banking, Insurance, Finance, Telco and etc. clients as a Consultant, Insource or Outsource.I have done 200+ Operations in this clients such as Exadata Installation & PoC & Migration & Upgrade, Oracle & SQL Server Database Upgrade, Oracle RAC Installation, SQL Server AlwaysOn Installation, Database Migration, Disaster Recovery, Backup Restore, Performance Tuning, Periodic Healthchecks.I have done 2000+ Table replication with Goldengate or SQL Server Replication tool for DWH Databases in many clients.If you need Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS Consultancy and Training you can send my email adress [email protected].-                                                                                                                                                                                                                                                 -Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS ve linux Danışmanlık ve Eğitim için  [email protected] a mail atabilirsiniz.

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