Can't load CSS mode in Emacs

[Jim Reisert AD1C]

I'm using the test version of Emacs 28.0.60.  I can't seem to load
css-mode (Cascading Style Sheets).  I get the following error in the
console window:

      0 [main] emacs-X11 1297 child_info_fork::abort: address space
needed by 'url-history-a9b2f6e8-97761513.eln' (0xAD0000) is already
occupied

Any idea what's going on?

I have not gone back and tried Emacs 27.

-- 
Jim Reisert AD1C, <jjreisert@alum.mit.edu>, https://www.ad1c.us