Ubuntu Kernel Panic- not syncing;attempt to kill init ! exitcode=0x0000000b

I was trying to install oracle 19c for Ubuntu. I was having problem with the yum repository configuration, so searching online I ran the command

yum install -y https://yum.oracle.com/repo/OracleLinux/OL7/latest/x86_64/getPackage/oracle-database-preinstall-19c-1.0-1.el7.x86_64.rpm

It was completed successfully, but now when I turn on the pc it gives to me a black window in which there is after some other lines

end Kernel panic - not syncing:Attempted to kill init ! exitcode=0x0000000b