Why it gets flagged
Because the proxy core xray.exe / v2ray.exe creates a network tunnel, antivirus often misjudges it as a trojan. It's a false positive, but the result is a deleted core file and v2rayN reporting "core not found" on launch.
Whitelist it
- First restore the deleted file from the antivirus quarantine / history.
- Add the whole v2rayN folder to the "trusted / excluded" directories.
- Windows Defender: Settings → Virus & threat protection → Exclusions → Add folder.
Firewall blocking
If it launches but can't reach the internet, check that the firewall allows v2rayN and the core inbound/outbound, adding an allow rule by hand if needed.