ArcSDE sdk can't connect to Oracle 19c

[HammadMuddassir]

I am using ArcSDE sdk 10.2.2 to direct connect with oracle 19c but its not working although it works fine when I use oracle 12c. 
The error I am getting is "Underline database error". Any suggestion will be helpful. Thanks in advance.

[KimGarbade]

Has the connection worked recently and absolutely no changes have happened to you software versions since?

If your Oracle version was just recently updated from 12c to 19c it could be a comparability/software version problem. Check out your current desktop (either Pro or ArcGIS desktop) version, and the version used to create or update your geodatabase.  

https://desktop.arcgis.com/en/arcmap/latest/manage-data/using-sql-with-gdbs/example-finding-the-geod...

Then look up compatability. You might need to upgrade your EGDB.  

It could also be that your SDK version is no longer compatible with your desktop or Oracle version. I'd start there.