Sounds like Emacs cannot find a fiff tool on the command line (or what ever git-gutter is trying to call) My suggestions would be: Install a diff CLI tool on windows and make sure Emacs can find it in the path (check path with SPC f e e ) Or disable git-gutter if it's causing an issue

Thanks John. I'll give that a try. What is git gutter?

Or try diff-hl rather than git-gutter https://develop.spacemacs.org/layers/+source-control/version-control/README.html#configuration

They are ways to show which lines have changed compared to the last commit in the Emacs gutter

I think the problem was with the github layer, which I don't use anyway. I've disabled it and it's not causing a problem anymore. Thank you always for your help, John.