In the latter half of 2016, Windows 10 Mobile users from all over the world reported being unable to sync emails from their Office 365 accounts on Outlook. They were also unable to sync their Office 365 accounts with OneDrive while using mobile data (2G/3G/4G). When attempting to do so, the affected users received an error message containing error code 0x85050042. This issue could affect any Windows 10 Mobile user trying to sync with their Office 365 accounts via Outlook or OneDrive on Mobile Data. It was especially rampant among those attempting to do so while roaming, i.e., using mobile data in a country different from their SIM/phone subscription origin. The error message read:
We’re not able to obtain the Single-Sign-on authentication token for your account.
caa70004 – The server or proxy was not found.
Error code: 0x85050042”
Users affected by this problem have confirmed that it only persists when using Mobile Data and that syncing is successful when connected to a WiFi network. Affected users have also confirmed that all other applications that require an internet connection work fine and all other email accounts apart from their Office 365 accounts sync fine on Mobile Data.
This problem does not affect any other areas of Windows 10 Mobile, but it does deny users access to their emails and OneDrive, which makes it aggravatingly frustrating. Removing your Office 365 account from the affected applications and then re-adding it while connected to a WiFi network will have no effect; the issue will still persist. In almost every single case, this issue is caused by a smartphone running on Windows 10 Mobile that has been configured to restrict background data. That is why the only known way to fix it is to:
- Expand the Notification area.
- Tap on All settings.
- Tap on Network & wireless.
- Tap on Data usage.
- Tap on Edit.
- Locate the Restrict background data option and set it to Never.
The problem should be resolved as soon as you configure the phone to never restrict background data. Once this is done, try syncing emails from your Office 365 account, or try syncing your Office 365 account with OneDrive, and see whether the issue has been fixed or not.