The issue is caused by changes in Windows as to how the AppAssure License encrypted registry values are processed.
To solve the issue, you need to have access to your AppAssure License File. You can get it from the AppAssure Portal (https://appassure.licenseportal.com)
Follow the steps below (all the command line examples should be run from an elevated Powershell console):
0. Make sure that there are no active jobs running on the core (PS C:\> get-activejobs -all). If any are running, wait for the jobs to finish.
1. Stop the AppAssure core service (AppAssureCore) (PS C:\> stop-service appassurecore)
1. Open RegEdit and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\AppRecovery\Core
2. Expand the Core key and navigate to the LicenseInfo key HKEY_LOCAL_MACHINE\SOFTWARE\AppRecovery\Core\LicenseInfo
3. Export the LicenseInfoKey to be on the safe side.
4. Delete the LicenseInfo subkey
5. Start the Core Service (AppAssurecore)
6. The GUI will come up and you will be asked for the license in a dialog.
7. Import the license file
You should have immediate access to the GUI.
If you have a chance, restart the core service to make sure that the issue is fully addressed.
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, see the following Microsoft Knowledge Base article: http://support.microsoft.com/kb/256986/EN-US/