A recent Jetpack update required more memory than previous ones. This resulted in a memory error and crashed websites with owners unable to login to their administrative dashboard.
Another problem with the recent Jetpack update seems to be that it’s no longer compatible with the Facebook API that counts shares.
Here’s the comment from 1 May 2015, on the WordPress.org about this issue:
Facebook recently changed the way that their API counts shares. Due to this change, the current method of counting shares that Jetpack uses is not working.
We are working on a new Jetpack release that will include a new method of counting Shares. Keep an eye out for a Jetpack update in the coming few days!
* * *
Hopefully they will get this fixed soon.