Google Deprecates ClientLogin May 2015 - How to switch to OAuth for iOS Sync
Google stopped supporting ClientLogin on May 26, 2015.
This affects iOS Devices that were set to sync with Google without using OAuth
NOTE: This procedure will delete all your Google data on your iPhone, and restore it from Google.
1. In iOS, edit your Accounts
2. Delete your Google Account.
3. Add it back. You will be prompted for the OAuth information.
NOTE: Deleting the account will delete all data associated with the account.
For further information please contact Apple support. This information is provided for information purposes to CompanionLink customers who are using Google sync to their iPhone and iPad devices.
If you use CompanionLink on your PC to sync with Google, you will need to enable OAuth. Click here for instructions.