Op 06-10-2023 om 06:50 schreef Andrew Tropin: > TLDR: > abort-to-prompt restores asyncs block level. > abort-to-prompt from a procedure scheduled with system-async-mark > doesn't restort asyncs block level. Looks like a duplicate or variant of <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48566> to me. (Maybe that's why you put me in CC?) It has a smaller/simpler reproducer. Don't have more information, though, beyond a guess that maybe the blocking/unblocking is actually going well but due to continuation shenanigans, the block level would need to (temporarily) become negative, and libguile/asyncs.c is too strict in its checks. Or maybe I'm confusing things with another bug ...