Hello Guix,

The hydra.gnu.org build farm has been off-line since yesterday ~4PM UTC
and will remain off-line roughly until the end of the week.  The FSF
sysadmins (it’s hosted at the FSF’s data center) are performing a major
storage upgrade that happens to need more time than expected.

In the meantime, if you use mirror.hydra.gnu.org, you’ll still get
substitutes, though not the latest one.

If you use berlin.guixsd.org, everything is fine; if you don’t, now is
the time to add it to your substitute URLs!  See
<https://gnu.org/software/guix/manual/en/html_node/Substitutes.html>.

Apologies for the inconvenience!

Ludo’.