This error is not really RMAN but NW specific. It appears if the SSH certificates on the NW clients 'are not in sync'. To test this, check the NW connectivity between both hosts, NW server and NW client as follows:   - On each server, try to open an nsradmin connection to the other site, for example:      On the NW client run    nsradmin -p nsrexec -s nw_server      On the NW server run    nsradmin -p nsrexec -s nw_client      Most likely, the connection will fail on one command.     -  To solve the issue, you must delete the certificates on each node - they will automatically be re-assigned with the next connection attempt.       To do this, run the following same command on each node:       nsradmin -p nsrexec -s localhost      Then delete the certificates as follows:      . type: nsr peer information; name:       p     (to verify that you are correct)      d     (to delete the resource)      q     (to quit the program) Then run the connectivity check (as mentioned above) again. If you successfully can 'login' all should be fine now.  
Need to help. I have an issue with RMAN backub oracle database running windows server 2016 (NMDA).139170:nsrdasv: Unable to obtain the user credentials from the lockbox due to the following error: 'Unable to authenticate with server xyz: Authentication error; why = Server rejected credential Thanks in advance
Unable to obtain the user credentials from the lockbox