Error with ModelingToolkit documentation example

I’m getting the following error from the first example in the Getting Started with ModelingToolkit example.

WARNING: could not import ModelingToolkit.t_nounits into Main

UndefVarError: `D` not defined

I found a workaround following instructions from earlier versions of the package by adding this before the example code:

@parameters t
D = Differential(t)

What is the best practices solution? It seems not the best to define these outside of @mtkmodel?

Are you on ModelingToolkit v9? Show ]st.

Thank you. I had updated all packages but missed that ModelingToolkit was prevented from updating due to Catalyst. Updating from 8.75 to 9.12 fixed the issue.