iPhone alerting you to upgrade Google Authenticator? DON'T — at least, not yet
If you know what Google Authenticator is, you know it adds a helpful second layer of security to your accounts, providing you with a six-digit code to enter at login in addition to your passwords. It's a way of making sure accounts are being accessed by a person who not only knows the correct password but is also in possession of the account owner's phone — in fact, once enabled, accounts using Google's 2-step authorization process can't be accessed without it.
So you can imagine how much trouble you might have accessing your accounts without your phone.
Or if, say, for the sake of example, Google pushed out an update to their Authenticator app that wiped out all user data, making the app forget your accounts and making it impossible to generate the codes required to log in.
Ha! That would be a really big mistake. Hoo, boy. Unfortunately, that's exactly what Google did last night. iPhone owners using Google's 2-step verification to access their Google accounts — or other accounts, as many third-party services use Authenticator — experienced their own personal data security crises today when asked for those verification codes if they had downloaded the app's version 2.0.0 update. The outage is being reported worldwide.
At the moment, Google has pulled Authenticator from Apple's App Store pending some sort of an update. So if you didn't install the latest version while it was available last night into this morning, you're probably safe — but if you get the update prompt, be sure to read the description and ensure that it addresses the loss of user data.
If you already installed the problem version of Authenticator, it's not clear yet how to proceed. Google has reportedly confirmed it's working on an update that to fix the data loss (The Next Web), but just to be on the safe side I've temporarily disabled 2-step verification on all accounts I can still access (at least, all the accounts I can access that I can remember used Google Authenticator for verification).
Other than that, the best advice is probably just to sit tight. Google doesn't seem to mention the problem on the official blogs it often uses for announcements, and as The Next Web notes, "we presume that there’s nothing the company can do for those who updated their version of the app already and are forced to start over again."