Suddenly started getting this error when running C-c C-a geiser-mode-switch-to-repl-and-enter from this source file. Came out of nowhere. This worked fine on the same source. I did some changes and stashed them with git stash essentially reverting to a file that ran fine before. Works without a glitch in DrRacket. Reinstalling geiser didn't help. Curiously C-c C-z back into source file and issuing C-c C-a again does enter! the module, but does'n run the body. All definitions available in the REPL.
Aside from doing stuff with git, I also replaced my Racket installation a couple of times.
Updated error message after reinstalling Racket
Why the hell does it try to read /Users/vkz/Library/Racket/planet/300/snapshot/cache/soegaard/sicp.plt/2/1/compiled/info_ss.zo I never ever reference it in my code. Bizarre
After killing the contents of ~/Library/Racket/ I stopped getting the wrong version message but the ?: module mismatch; and the rest