Oracle Error -  "OCIEnvCreate failed with return code -1 but error message text was not available".

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    ISSUE:

     

    When trying to connect to an Oracle database you receive the following error: "OCIEnvCreate failed with return code -1 but error message text was not available"

     

     

    CAUSE:

     

    One of the two following circumstances is the likely cause:

     

    1, You are using an unsupported version of the Oracle Client (older than 11.2) on Windows 7.

    2, DLLs from a previous installation of Oracle Client have been left on the system, causing a conflict.

     

     

    SOLUTION:

     

    1, Install a supported version of the Oracle Client.

    2,  Perform a search for "OCI.DLL" on the local machine.  If you find any instances of this file in any location other than your ORACLE_HOME rename or delete it.      If in doubt, uninstall the Oracle Client, then perform the search again.  Anything that is leftover is the culprit.