Welcome!
The error message in the screenshot makes it look like you have a very old version of Convex.jl; that references MathProgBase which we stopped using in Convex a few years ago.
How did you update? Try
using Pkg
Pkg.add(PackageSpec(name="Convex", version=v"0.14.5"))
If you get an error, copy the whole message here.
Also, please read this post: Please read: make it easier to help you.