Do I "require" the Oracle database client 12.1 software on my workstation in order to Create/Enable Enterprise GeoDatabase on Oracle 12.1 or even to connect? Can I not use Oracle Database Client 11.2? If I only have 12.1 client, I cannot connect to any of my Oracle 11g databases. I am unable to connect using ArcGIS Desktop 10.5.1, it just spins when I make a simple sde connection with 11.2 client software which I prefer to use. There has to be a way I can connect using 11.2 client with either a 11g or 12c oracle database.
I am not using Pro so I do not have the 64bit client. The 32 bit is set as the first variable in the system PATH. I have the Oracle 12.1 admin client, not instant client. I am able to tnsping and sqlplus into my Oracle 12.1 databases with no issues at all, it is ArcGIS Desktop 10.5.1 that is, 10.4.1 and below works with Oracle 12.1.
What do the Connection Properties look like in ArcCatalog when you create the SDE connection (Please provide a screenshot)?
Can you revert back to an 11g Oracle Client?
I believe I was testing an Oracle 12c Client and I had issues making the connection to Oracle SDE, so I stayed with Oracle 11g Client. My org also has now migrated to the Instant Oracle 11g client and so far it has been successful.
Do you have access to Pro to see if your Oracle 12c Client connections work better in that environment? You would need the 64-bit Oracle Client though.