I am planning to upgrade 126.96.36.199 database to 19.3.0. My question is about patching the database. The source 11gR2 database is never patched, I am saying because lsinventory shows "There are no Interim patches installed in this Oracle Home". Oracle support DOC ID 2539751.1 says to apply 28553832 one-off patch before I upgrade database from 188.8.131.52 to 19c. I wanted to make sure about the , is this the only path or are there more patches need to be applied before I upgrade. Please let me know your thoughts.
It is the only one mentioned so there shouldn't be any. The bug is related to clusterware so you might not even hit this bug (for instance if you don't use clusterware). You could do a test upgrade without the bug and see whether it succeeds. If it does so, then there shouldn't be a need for the patch in your case.