If cPanel update failed with the following message;

===

Fatal: Your RPM database appears unstable. It is not possible at the moment to install a simple RPM.

===

The error is because of the corrupted RPM database. You can resolve this via the following steps;

===

1. mkdir /root/old_rpm_dbs/

2. mv /var/lib/rpm/__db* /root/old_rpm_dbs/

3. rpm --rebuilddb

4. Then run, #upcp –force

===

Now cPanel update will complete successfully.