If you tried to downgrade, you might see this error. You may need to use a third-party uninstaller to fully remove traces of newer iTunes versions first.
Downloading iTunes 10.13.99 is an act of nostalgia and defiance. It is not a practical daily driver for someone deep in the iCloud/Apple Music ecosystem. However, if you have a massive library of MP3s and FLACs (converted) and hate the new Music app's tendency to mishandle metadata, this version is a sanctuary. itunes 10.13.99 download mac