After upgrading to Rapid Recovery, the core console will not open or if it does open, it is stuck on loading. In addition, any PowerShell cmdlets will be non responsive.
If the core console does load, it will be extremely slow or non-responsive and have a warning regarding MongoDB "Recovery Core MongoDB Service is disconnected. Please verify your connection settings and restart the service if needed." Looking at the MongoDB service it it will be running.

You will find the following error in AppRecovery logs:
ERROR 2017-07-06T11:20:53 [1953] - Replay.ServiceHost.Implementation.Hosting.ServiceHost (RequestUri=https://localhost:8006/apprecovery/api/core/status/latestEventsInfo ClientAddress=::1:61727)
Service Host Error: Service error while handling request [GET https://localhost:8006/apprecovery/api/core/status/latestEventsInfo]: Placeholder mismatch with format string [Failed to perform the database server connection test. Failure reason: A timeout occured after 30000ms selecting a server using CompositeServerSelector{ Selectors = ReadPreferenceServerSelector{ ReadPreference = { Mode : Primary } }, LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 } }. Client view of cluster state is { ClusterId : "2", ConnectionMode : "Automatic", Type : "Standalone", State : "Disconnected", Servers : [{ ServerId: "{ ClusterId : 2, EndPoint : "Unspecified/localhost:27017" }", EndPoint: "Unspecified/localhost:27017", State: "Disconnected", Type: "Unknown", HeartbeatException: "MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> MongoDB.Driver.MongoAuthenticationException: Unable to authenticate username 'RapidRecoveryClient' on database 'AppAssure'. ---> MongoDB.Driver.MongoCommandException: Command authenticate failed: auth failed.