Sonarr is no longer compatible with OSX versions < 10.15 (Catalina) due to .NET incompatibilities.
codesign --force --deep -s - /Applications/Sonarr.app && xattr -rd com.apple.quarantine /Applications/Sonarr.appopen /Applications/Sonarr.appSonarr uses a bundled version of ffprobe for media file analysis and does not require ffprobe or ffmpeg to be installed on the system. If Sonarr says Ffprobe is not found this can typically be fixed with a reinstall.