Thanks for your input, Luis! TL;DR: this is the same bug as #1017739:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1017739 While trying what you suggested, I had again the same error after: - quitting Emacs; - deleting ~/.emacs.d; - upgrading again to the current version of the Emacs packages in sid; - restarting Emacs as normal user. Then I realized I had root-owned files in ~/.emacs.d/eln-cache such as subr--trampoline-6d616b652d73706172736. I pass you some details like trying an 'strace -f' and looking if any of the Emacs packages ships suid binaries... in the end, I understood that it was the *upgrade* to Emacs 28 that created these files under my home dir, not the emacs binary run as normal user (yes, I used 'su' without '-'). Pheeeeeew! :) Regards -- Florent
