The Cisco Tetration agent MSI installer uses Microsoft Windows Installer services to perform installations during upgrades. If the installer encounters a file from a previous agent installation that it cannot overwrite or remove, the installer will queue this file and request a reboot from the OS.
In the 18.104.22.168 release, this issue will trigger a reboot immediately. With the 22.214.171.124 release, this issue will prevent the reboot, but the files will still be pending and waiting for a manual reboot.
With the 126.96.36.199 release, this pending reboot can lead to mixed code running in the environment if the files queued for replacement by the Microsoft Windows Installer are executables. If the system is manually rebooted, the installation will finish, the pending files will be copied, and the agent will be fully running on the updated code.