Supported upgrade path
You can upgrade Couchbase Server from one major version to another. For example, you can upgrade directly from version 3.0.3 to 4.0.0, and also from version 2.5.2 to 4.0.0. See Upgrade matrix for more information on the supported upgrade paths.
However, when I follow the “Upgrade matrix” link, it says we can go from 2.5.x to 4.x.
So, can I upgrade from 2.5.1 or 2.5.0 directly to 4.0 or do I need do an interim upgrade to 2.5.2 or 3.x ?