Please note: This solution involves running a repair on the core installation. It will remove any custom binaries that you have installed. Please make a note of a custom binary, if present, you have and re-install it after the repair.
To find what binaries are installed please follow the steps outlined in the KB below.
To resolve the issue follow the steps below:
1. Stop the AppAssure Core service. Please see the KB below on how to correctly stop the core service.
2. Browse to the C:\Program Files\AppRecovery\Core\CoreService folder and rename the MongoDB.Driver.dll file to .old.
3. Make sure you don't have the Services window open.
4. Open Control Panel -> Programs and Features.
5. Find AppAssure Core and click on Change and select Repair.
6. Once repair process completed successfully open Services and confirm that the AppAssure Core MongoDB service is now present.