ODA/KVM ORA-38706/ORA-04031 during dataguard configuration

During a dataguard configuration in a DBSystem 19.19, using the configure-dataguard command, the following error occurred

Errors in file /u01/app/oracle/diag/rdbms/emdevu/emdev1/trace/emdev1_ora_44401.trc:
ORA-38706: Cannot turn on FLASHBACK DATABASE logging.
ORA-04031: unable to allocate 15937408 bytes of shared memory ("shared pool","unknown object","sga heap(1,0)","flashback generation buffer")
ORA-38706 signalled during: alter database flashback on …
Control autobackup written to DISK device

The workaround is sto set the following parameter in init.ora and bounce the database

ALTER SYSTEM SET "_allocate_flashback_buffer"=TRUE SCOPE=SPFILE;

The shape the DBSystem was odb2/32GB.

More info in the bug 32504243.