It says the workbench.library was removed to save space. OS 3.5 and 3.9 don't need it to load.
And if I remove my belt it will save space in my luggage, but that doesn't mean my pants won't fall down, or that my wardrobe will be more functional.

j/k, I've been loading workbench.library off disk for years. Works fine. Off-hand I think the latest version is 45.134.