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Windows: 'TNS: Protocol Adapter Not Loadable'Error When Trying To Connect From Another Oracle Home TNS-12557 (Doc ID 556895.1)

Last updated on MARCH 31, 2022

Applies to:

Oracle Net Services - Version to [Release 10.2 to 12.1]
Microsoft Windows x64 (64-bit)


A Windows machine has two ore more Oracle homes installed. Connections from the usual home are working, but when trying to connect from the other Oracle home (by changing the environment) it fails with error: “TNS-12557: TNS: Protocol Adapter not Loadable”.

A client trace shows these errors:


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