Hello everyone, Someone reported the exact same issue today on IRC [1], with polkit being the culprit. With a bigger backtrace, the match error happens at line 901 in guix/gexp.scm, in the match inside the return part of lower-inputs. This suggests that lower-object doesn't manage to return a derivation but only the polkit package. I suspect that this has to do with the complex polkit package interactions that we have, with polkit being an identifier syntax for either polkit-mozjs or polkit-duktape, with duktape package/inherit'ing polkit-mozjs with is itself replaced by polkit-mozjs/fixed. Maybe there's an interaction with the caching as well, while grafting and looping? I've tried to reproduce this locally by building a gexp that has either polkit, polkit-duktape or polkit-mozjs as an input, enabling or disabling fallback or grafting, to no avail. Maybe someone else has another idea? [1] https://logs.guix.gnu.org/guix/2022-04-22.log#154402 Best, -- Josselin Poiret