Hi,
Can a newly deployed 5.0.1 Community Edition server join a cluster of a few 4.5.1 Community Editions servers?
If not, what steps are recommended to quietly migrate from the old one to the new one without losing the data?
Thanks for the future help,
Alex
It looks like upgrade from 4.5 to 5 is possible according to the upgrade matrix.
Start here:
https://developer.couchbase.com/documentation/server/current/install/upgrade.html
Then explore the upgrading options (I don’t know what you consider “quiet” 
- https://developer.couchbase.com/documentation/server/current/install/upgrade-strategies.html
Hi @alex1, Yes, you can upgrade 4.5.1 cluster to 5.0.1 using the Online Rolling Upgrade strategy as @matthew.groves mentioned.