I know this problem has been asked a few times, but I have to ask again because I know Microsoft won't respond twice on a question.
I had this problem 2 times and I reinstalled Windows 10 Technical Preview 2 times, it is frustrating.
Both times had not displayed any error messages unless I run one the the apps using the "Run". Also, it is ironic if you have to update to get rid of the problem while Windows Update had moved to a metro app.
First time, trying "wuapp", got a message like "cannot open app because app manager is not running".
I then tried "sfc /scannow", but always stopped at 2%:
C:\WINDOWS\system32>sfc /scannow
Beginning system scan. This process will take some time.
Beginning verification phase of system scan.
Verification 2% complete.
Windows Resource Protection could not perform the requested operation.
I then tried startup CMD, but found that CMD, startup repair and other options
require an administrator to be logged in... I mean, how?!
I reinstalled Windows 10 Tech Preview using this method:
1. Log in to the broken Windows
2. Run the setup disc
3. "Update" the PC to 10 again without losing data
Now, I get a "this app does not support the contract specified or is not installed" error message.
I ran the powershell command using administrator privileges found on superuser.com:
Get-AppxPackage | % { Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppxManifest.xml" -verbose }
It reinstalled some apps like "Sport" and "Weather" but had error messages for almost all apps it detected:
Add-AppxPackage : Deployment failed with HRESULT: 0x80073CF6, Package could not be registered. error 0x80070002: Windows cannot register the package because of an internal er ror or low memory. NOTE: For additional
information, look for [ActivityId] 1b879ac4-3f95-0001-27ef -871b953fd001 in the Event Log or use the command line Get-AppxLog -ActivityID At line:1 char:23
It did fix the problem of opening apps(not that I am sure), I can now open Settings and Store through complicated processes, but it didn't fix the start menu and the action center.
What I found is that my PC always had a recurring crash with 0x00000021 many times a day, before settling with the no start menu, action center and metro app problem.
I don't want to keep reinstalling Windows 10 since it doesn't "solve" the problem, but please help!