Cause: The installer looks for a specific registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Cadence Design Systems\Release\16.5\CDSROOT.
Solution: If you manually copied an SPB folder from another machine, you cannot install hotfixes. You must install from an original installer to build the registry entries.
Based on historical release notes, common fixes included: orcad 165 hotfix spb 165 updates fix
Early releases of SPB 16.5 had several known issues that hotfixes incrementally resolved: Cause: The installer looks for a specific registry