If you tried to use Cydia today, then you probably received the above message after a few minutes of waiting. It seems that the Cydia servers have a small problem today and this has an impact not only on the main page of the application but probably also on the servers where the SHSHs are kept. saurik didn't say anything about this downtime, but I recommend you not to try any restore with SHSHs from the Cydia servers because you might wake up with some unpleasant surprise.
Unfortunately, due to this error, you will not be able to see the new packages published in Cydia, but be patient because the problem will definitely be solved in the shortest time.
UPDATED: Problem has been solved!
