Does Oracle 19c support Ubuntu?
Oracle does NOT support Ubuntu. From the documentation:
https://docs.oracle.com/en/database/oracle/oracle-database/19/ladbi/operating-system-checklist-for-oracle-database-installation-on-linux.html#GUID-E5C0A90E-7750-45D9-A8BC-C7319ED934F0
The following Linux x86-64 kernels are supported:

Oracle Linux 8.1 with the Unbreakable Enterprise Kernel 6:
5.4.17-2011.0.7.el8uek.x86_64 or later Oracle Linux 8 with the Red Hat Compatible kernel: 4.18.0-80.el8.x86_64 or later

Oracle Linux 7.4 with the Unbreakable Enterprise Kernel 4:
4.1.12-124.19.2.el7uek.x86_64 or later Oracle Linux 7.4 with the Unbreakable
Enterprise Kernel 5: 4.14.35-1818.1.6.el7uek.x86_64 or
later Oracle Linux 7.7 with the Unbreakable Enterprise Kernel 6:
5.4.17-2011.4.4.el7uek.x86_64 or later Oracle Linux 7.5 with the Red Hat Compatible Kernel: 3.10.0-862.11.6.el7.x86_64 or later

Red Hat Enterprise Linux 8: 4.18.0-80.el8.x86_64 or later

Red Hat Enterprise Linux 7.5: 3.10.0-862.11.6.el7.x86_64 or later

SUSE Linux Enterprise Server 15: 4.12.14-23-default or later

SUSE Linux Enterprise Server 12 SP3: 4.4.162-94.72-default or later


Ubuntu is an entirely different branch of Linux, and no matter how many people claim they have hacked it to work, it is NOT supported and results are NOT guaranteed.