I haven't worked with trying to get CyberArk to sync with a mainframe app directly. Have you reached out to CyberArk directly to see if they can troubleshoot that for you?
If CyberArk doesn't seem to support the interface for the mainframe app (not supplying the old password), then you could consider having a Blue Prism automation update the mainframe app password, but that might entirely change your architecture for password management. I think it'd be best to reach out to CyberArk.
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Dave Morris
3Ci @ Southern Company
Atlanta, GA
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Dave Morris, 3Ci at Southern Company