Why are all Google apps crashing?

[curiouscabbage]

I've got a Nexus 5 running Android L, and I've just done a standard update of all my apps to their latest version - no Google app is running now, though. Not Google Keyboard, nor Keep, nor Camera, nor Plus. This, obviously, is a very big issue. I just get a message like "Unfortunately, Gmail has stopped."

What is going on, and why is everything crashing? How can I make everything work again?

 

[kilskev]

Have you tried clearing google services cache

Sent from my AOSP on HammerHead using Tapatalk

 

[curiouscabbage]

This hasn't worked.