org-mode error: Invalid function (date date)

When trying to open org-agenda agenda, I'm getting an empty agenda with the message

Invalid function (date date)

Someone has a similar thing here for Doom Emacs: https://github.com/doomemacs/doomemacs/issues/4862

Someone has good advice here:

I think it's because you have an updated org-mode was installed (actually compiled, I think) while the built-in org-mode package was already loaded. I've had exactly that problem when trying to access the agenda.

– Invalid function: (date date) : orgmode

Recompiling org locally seems to be the suggestion.

cd ~/.emacs.d/elpa/27.2/develop
rm org* -rf

Probably could have removed just the org package specifically, but just blased them all away.

Restart Emacs. It downloads and installs/compiles the packages I removed.

Agenda is back in business!