When attempting to connect to an Oracle database from an ArcGIS application, the following error occurs:
"Client software failed to load. Be sure the database client software is installed and configured correctly."
This error may occur for the following reasons:
A. No client is installed on the ArcGIS for Desktop machine.
B. Only the 64-bit client is installed when attempting to connect to Oracle from ArcMap or ArcCatalog, which are 32-bit applications.
C. Only the 32-bit client is installed when attempting to connect to Oracle from ArcGIS for Server or ArcGIS Pro, which are 64-bit applications.