Date: February 5, 2018
Time: 4:13 pm to 5:35 pm PST
Tests did not start consistently on some Android emulator, iOS simulator and OS X VMs.
Why Did It Happen:
A network configuration error prevented servers in one of the data centers from being able to access essential services.
What did we do to fix it:
We fixed the network configuration manually.
What are we doing to prevent it from happening again:
We permanently set up a whitelist that would prevent this from happening again, and we updated the relevant automated configuration playbooks.