Why does system not booting after upgrading from 5.4 to 5.11 and not finding the root volume?

Solution Verified - Updated 2016-04-18T18:21:38+00:00 -

Issue

Updated Red Hat Enterprise Linux 5.4 to 5.11
Rebooted but kernel panic appeared with both old kernel entry and new one too, mentioning that root and all other filesystem volumes not found.

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