Foster upgraded to macOS High Sierra and now his Final Cut Pro 7 video editing program won't work. Why is Apple allowed to break people's apps and force them to pay for new versions? Leo says that sometimes when upgrading to a new OS, it has to leave apps behind, especially 32 bit apps. Apple would have done better to warn customers that it could happen. Leo says that most apps can be updated to work again, though, so he should go to his software websites and get the latest version. If it doesn't work after that, then it's been left behind. That's why running Windows is a better option if he uses software that is older. Microsoft has kept legacy apps in the code for users to run older software. But even Microsoft is now leaving older programs behind. It's the only way to keep up with the future.
Foster should check out this white paper from Apple on moving to Final Cut X.
One option is to roll back from High Sierra and then reinstall his original programs.