Users of Bitdefender Antivirus are reporting that the security software has suddenly stopped working. After installing an update, users are seeing errors that state “Bitdefender Security Service (vsserv.exe) is unavailable at the moment”” The issue was caused by an update not being completely delivered by certain customers. Users need to install a new update and then reboot their computer to get it to work properly again. Uninstalling and reinstalling the program does not work for every user.”
Source: https://www.bleepingcomputer.com/news/security/bitdefender-ironically-stopped-working-on-safer-internet-day/