Bitdefender is currently marking Parsec as a virus. We are filing a false positive report with them, but they in particular are catching our Discord integration (Harmony.exe) as an issue. They're removing that integration from the application causing a failed installation. You should uninstall Parsec completely and follow these steps from Bitdefender prior to attempting to reinstall. After that, reinstall Parsec. But if you get this message, follow the steps below.
To reinstall Parsec, please confirm that ALL processes in Task Manager with Parsec listed are ended (including pservice.exe). After that, uninstall Parsec completely using Windows Uninstaller. Restart your computer and only then, please reinstall Parsec.