Sometimes the Core client certificates are changed when upgrading either the AppAssure or Rapid Recovery software or installing Windows updates. When the certificate is changed, the connection to the agents will fail with an “authentication failure” error message.
After installing Windows updates on the Core and agent servers, agents are unable to authenticate to the Core. Additional pairing errors also prevent users from adding or re-adding agents to protection.You might encounter log error messages and events similar to the following.
Applicable Log Errors
ERROR [date and time]  – Replay.ServiceHost.Implementation.Hosting.ListenerService ()
Caught exception processing HTTP operation
System.ObjectDisposedException: Safe handle has been closed
ERROR [date and time]  – Replay.ServiceHost.Implementation.Hosting.ServiceHost (RequestUri=https://yourdomain:8006/apprecovery/api/agent/servicehost/restart ClientAddress=192.168.255.255:65427)
Service Host Error: Service error while handling request [GET https://yourdomain:8006/apprecovery/api/agent/servicehost/restart]: The handle is invalid
Request Uri: https://yourdomain:8006/apprecovery/api/agent/servicehost/restart
Client Address: 192.168.255.255:65427
Identity: Negotiate:NT AUTHORITY\SYSTEM
Applicable Eventvwr Events
Log Name: System
Date: [date and time]
Event ID: 36885
Task Category: None
Re-pair the agents:
If the Core client certificates were changed after installing Windows updates, please refer to this Microsoft article.