From the WordPress team:
Thanks for getting in touch, and I'm sorry you've had this problem. We've received several reports about this error and our development team is currently looking into it.
We'll be back in touch as soon as we have any further details.
From what was said here from Jerremy it looks like this is a known issue to JetPack and is being looked into. To download an old version (although this is not reccomended)go here then scroll down until you see 'Other versions' and select the other version to download. I do not see how this will help but there you go.