Oracle Connection to Docker Container Failed on Ubuntu 24.04

What Was the Problem?

After upgrading to Ubuntu 24.04, connections to an Oracle database in a Docker container failed.  These connections were working before the upgrade.

• SQL*Plus: ORA-12637: Packet receive failed
• "sqlnet.ora" (TRACE_LEVEL_CLIENT=user): Fatal NI connect error 12170
• Oracle SQL Developer Extension for VSCode: Failed to connect

It Was Not AppArmor

I found many entries about Docker not starting after an Ubuntu upgrade.  While I don't know the root cause of this problem, no changes to AppArmor are needed to solve this problem.

What is the Interim Fix?

I found several fixes. I included links to websites.

SQL*Plus/SQL*Net:

Update "sqlnet.ora" File - Add "DISABLE_OOB=ON" to disable Out-of-Band communication.  Note: The location of the "sqlnet.ora" file can be based on the environment settings of ORACLE_HOME or TNS_ADMIN.

Oracle SQL Developer Extension for VSCode

Update "Advanced" Tab in "Update Connection" - Add a new name "oracle.net.disableOob" with a value of "true" to disable Out-of-Band communication.

What is the Root Cause?

I don't know.  I have not found it.  I assume there is a loss of functionality when Out-of-Band communication is not available for an Oracle client.  I will continue to follow this and add updates as I find them.