Issue: After upgrading from Build 16299.0 to 16299.15, you might lose all previously installed Feature-on-Demand (FOD) packages such as Windows Media Player, language features, etc. during the upgrade. If you upgraded to Build 16299.15 from an older build such as Build 16296 – you are not impacted.
This issue occurs due to a bug in our servicing stack where the FOD packages are incorrectly “dead-ended”. When this happens, setup removes these “dead-ended” FODs during upgrade. By losing these FOD packages, you might experience a range of issues such as your email not syncing in the Mail app, different elements of UI not appearing in Settings or apps like Mail, font disappearing, Cortana not working correctly and the loss of Windows Media Player.
To get out of this state: You will have to manually reinstall your missing FOD packages. There may be some cases where some missing FODs are automatically reinstalled, such as those tied to the languages associated with your profile. Other features may require command line operations to install.
If all your email accounts stopped syncing new emails or you are unable to add a new email account: One of the main components for email functionality is also a FOD.
You can reinstall that component via this command line in an admin command prompt: C:\WINDOWS\system32>dism /online /Add-Capability /CapabilityName:OneCoreUAP.OneSync~~~~0.0.1.0
Future upgrades to builds newer than Build 16299.15 shouldn’t remove the FODs that were reinstalled.
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