Upgrade cucm from 8.5 to 9.1 : Security issue (CTL Files)
What version of 8.5.1 are you on? Look out for https://tools.cisco.com/bugsearch/bug/CSCtn50405/ which causes certificates to not be backed up properly so when you do the backup/restore you could run into problems. The good news is that you are using CTLs which uses a physical token so you cannot run into a state where the phones do not trust anything (unless the tokens are lost/damaged of course).
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.