Adam Kandur skribis: > Hi, i built 2.0.8 and error disappeared. could you tell where in manual i can read about donwgrading packages If SBCL is in your main profile, you could downgrade it with: --8<---------------cut here---------------start------------->8--- guix package --roll-back guix package --upgrade --do-not-upgrade=sbcl --8<---------------cut here---------------end--------------->8--- Or you could create an environment with "guix time-machine": --8<---------------cut here---------------start------------->8--- guix time-machine --commit 21e79225352a5e78aa329b6cd213eb553862c363 -- environment --ad-hoc sbcl --8<---------------cut here---------------end--------------->8--- Here 21e79225352a5e78aa329b6cd213eb553862c363 is the commit just before the patch upgrading SBCL to 2.0.9.