Why do I see "An update to your account is required" on sign in?
We’ve recently transitioned Google Apps accounts to a new account infrastructure so that Google Apps accounts are able to access the majority of Google products, just like a Google Account. As a result, you have a conflicting account because you have used your Google Account to manage AdWords, which is now available through Google Apps. Using the same email address to sign in to both these accounts would create confusion as to which account you wanted to sign in to. To avoid this confusion, you either have to move data from your Google Account's AdWords account into your Google Apps AdWords account or associate your Google Account AdWords account with a new email address. There also are several logistical and privacy considerations you should take into account before moving your data.
How is a Google Account different from a Google Apps account?
Although Google Apps and Google Accounts allow you to access several of the same Google products, they're different types of accounts. A Google Account is a unified sign-in system that provides access to a variety of free Google consumer products -- such as Gmail, Google Groups, Google Shopping List, Picasa, Web History, iGoogle, and Google Checkout -- administered by Google. Google Apps provides access to products powered by Google but administered by your organization.
The Google Apps transition
The Google Apps transition will move Google Apps accounts into the Google Account infrastructure, so you can use your Google Apps account to access the same Google products and services that Google Accounts holders can. Essentially, your Google Apps account will function more like a Google Account. For instance, you'll be able to sign in and use products like Blogger and Picasa with your Google Apps account, if your domain administrator allows.
If you've used other Google products outside of the ones you can access with your Google Apps account that you previously managed through you Google Apps account, such as Blogger, Picasa, Reader, or AdWords, you may have created what's known as a conflicting account. A conflicting account is an account hosted on the Google Account infrastructure, created with the same email address as your Google Apps account. Having a conflicting account means that you have two accounts with the same email address, hosted on two different name storing databases.
When the Google Apps account transitions into the Google Account infrastructure, only one instance of the account name can appear in the Google Account name database. To resolve this conflict in account names, the data in the personal Google Account will need to be re-associated with a different account name. The next time you sign in to your conflicting account, you will be asked to change the name you use to sign in, in order to continue accessing the data in your conflicting account.
For instance, your Google Apps email address is firstname.lastname@example.org. A while back, you may have signed up for AdWords with this email address, which created a personal Google Account. Since we've moved your Google Apps account to the Google Account infrastructure, your the data in your personal Google Account will need to be re-associated with a new name because there can't be two email@example.com accounts with the same name. The first time you sign in to your conflicting account of firstname.lastname@example.org to access AdWords, you will be prompted to re-associate your data to a different account name. Once you do so, you'll need to use the new account name to sign in to AdWords and access your AdWords data.