See here:
Basically, I got it working by removing the packages from all my projects. Then doing this:
But it appears using a temp directory was insufficient to isolate the problem. What I did is remove all those packages from my project then run
]gc --all. I saw this did delete them in~/.julia/packages.
Then reinstalled the packages one by one. The order maybe matters but if you see an error then remove the last one, do the garbage collection, then try with another.
I think in the end just installing one by one after making sure the packages were actually deleted worked (by the package manager, doing it manually sounded like a bad idea).
Edit:
People who know better than I thought it was an issue with how the package manager deals with the new extension packages introduced in version 1.9. So I assume this issue is being worked on, but for now that worked for me…