Can't start emacs (spacemacs) anymore: Invalid read syntax: Invalid byte-code object

I had the same issue this morning.

I'm using emacs 28.0.50 on Kubuntu 19.10.

My issue was gone by deleting use-package:

rm -rf ~/.emacs.d/elpa/use-package-*

# if using the `develop` branch:
# rm -rf ~/.emacs.d/elpa/<your emacs version>/develop/use-package-*

and re-installing it:

emacs -q

eval:

(progn
  (require 'package)
  (add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/"))
  (package-initialize)
  (package-refresh-contents)
  (package-install 'use-package)
  (require 'use-package)
)