Windows 7 system, version 6.1 Build 7601, which hasn't received updates for a while. This has led to difficulties in installing Kaspersky Endpoint Security for Windows (version 12.3.0.493), preventing it from contacting the administration server of KESC.
To address this issue, i have decided to update the system using the "Update for Windows 7 for x64-based Systems (KB3125574)" patch.