Microsoft has issued some help to Windows Insiders left unable to manage their Microsoft Accounts or accounts associated with Mail, Calendar and Contacts after upgrading from Build 16299.0 to 16299.15. In additional Insiders might have lost all previously installed Feature-on-Demand (FOD) packages such as Windows Media Player, language features, etc. during the upgrade.
Issues arose because of a bug in the servicing stack where the FOD packages were incorrectly “dead-ended”. When this happens, setup removes these “dead-ended” FODs during the upgrade. By losing these FOD packages, Insiders would 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, fonts disappearing, Cortana not working correctly and the loss of Windows Media Player.
To get out of this state: Insiders will have to manually reinstall the 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 an FOD (Feature-on-Demand) feature.
The component needs to be reinstalled via command prompt, using these steps:
Right-Click on the Start Menu and select Command Prompt (Administrator) or PowerShell (Administrator)
Select ‘Yes’ to allow the app to make changes to your device.
At the command prompt enter the following: dism /online /Add-Capability /CapabilityName:OneCoreUAP.OneSync~~~~0.0.1.0
Press Enter. The reinstall will start progress. If you aren’t seeing progress, you can press Enter again.
Once the reinstall is complete, you will be prompted to restart your device. If not prompted, you will need to restart the device yourself.
After restarting, confirm your account is syncing correctly in the Mail app. If the account does not appear to be syncing correctly, check try the following:
In the Mail app: Settings -> Manage Accounts -> Select the account. If the Account settings dialogue is available, the component was successfully reinstalled.
If the account is still not syncing, delete and re-add the account again in the Mail app: Settings -> Manage Accounts -> Select the account -> Select ‘Delete account from this device’ -> Click ‘Delete’. Once the account is removed, select ‘Add Account’ to re-add it.
If Cortana is blocking the start menu or Cortana Speech is not working: Please follow these steps to fix the Cortana issue.
Open Settings and navigate to Time & Language
Click on Region and Language
Click on the Windows display language and then click Options
Under Language Options, wait for the available packages to load, and then click to install the missing packages (Speech)
After these are installed, restart your computer and the issue will be resolved.
If you are missing Windows Media Player: You can add Windows Media Player by going to Settings > Apps > Apps & features, clicking on “Manage optional features” and then “Add a feature” and select Windows Media Player to install.